diff --git a/frontend/src/components/FailedDocumentViewer.tsx b/frontend/src/components/FailedDocumentViewer.tsx
index 8b7b0fb..b49d3b8 100644
--- a/frontend/src/components/FailedDocumentViewer.tsx
+++ b/frontend/src/components/FailedDocumentViewer.tsx
@@ -91,7 +91,7 @@ const FailedDocumentViewer: React.FC<FailedDocumentViewerProps> = ({
     }}>
       {documentUrl && (
         <>
-          {mimeType.startsWith('image/') ? (
+          {mimeType?.startsWith('image/') ? (
             <Box sx={{ textAlign: 'center' }}>
               <img
                 src={documentUrl}
@@ -111,7 +111,7 @@ const FailedDocumentViewer: React.FC<FailedDocumentViewerProps> = ({
               style={{ border: 'none', borderRadius: '4px' }}
               title={filename}
             />
-          ) : mimeType.startsWith('text/') ? (
+          ) : mimeType?.startsWith('text/') ? (
             <Box sx={{ 
               fontFamily: 'monospace', 
               fontSize: '0.875rem',
@@ -133,7 +133,7 @@ const FailedDocumentViewer: React.FC<FailedDocumentViewerProps> = ({
           ) : (
             <Box sx={{ textAlign: 'center', py: 4 }}>
               <Typography variant="body1" color="text.secondary">
-                Cannot preview this file type ({mimeType})
+                Cannot preview this file type ({mimeType || 'unknown'})
               </Typography>
               <Typography variant="body2" color="text.secondary" sx={{ mt: 1 }}>
                 File: {filename}
diff --git a/frontend/src/components/__tests__/FailedDocumentViewer.test.tsx b/frontend/src/components/__tests__/FailedDocumentViewer.test.tsx
new file mode 100644
index 0000000..c5b4a06
--- /dev/null
+++ b/frontend/src/components/__tests__/FailedDocumentViewer.test.tsx
@@ -0,0 +1,493 @@
+import { describe, test, expect, vi, beforeEach, afterEach } from 'vitest';
+import { render, screen, waitFor } from '@testing-library/react';
+import { ThemeProvider, createTheme } from '@mui/material/styles';
+import FailedDocumentViewer from '../FailedDocumentViewer';
+import { api } from '../../services/api';
+
+// Mock the API
+vi.mock('../../services/api', () => ({
+  api: {
+    get: vi.fn(),
+  },
+}));
+
+const theme = createTheme();
+
+const defaultProps = {
+  failedDocumentId: 'test-failed-doc-id',
+  filename: 'test-document.pdf',
+  mimeType: 'application/pdf',
+};
+
+const renderFailedDocumentViewer = (props = {}) => {
+  const combinedProps = { ...defaultProps, ...props };
+  
+  return render(
+    <ThemeProvider theme={theme}>
+      <FailedDocumentViewer {...combinedProps} />
+    </ThemeProvider>
+  );
+};
+
+// Mock Blob and URL.createObjectURL
+const mockBlob = vi.fn(() => ({
+  text: () => Promise.resolve('mock text content'),
+}));
+global.Blob = mockBlob as any;
+
+const mockCreateObjectURL = vi.fn(() => 'mock-object-url');
+const mockRevokeObjectURL = vi.fn();
+global.URL = {
+  createObjectURL: mockCreateObjectURL,
+  revokeObjectURL: mockRevokeObjectURL,
+} as any;
+
+describe('FailedDocumentViewer', () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+  });
+
+  afterEach(() => {
+    vi.clearAllMocks();
+  });
+
+  describe('Loading State', () => {
+    test('should show loading spinner initially', () => {
+      // Mock API to never resolve
+      vi.mocked(api.get).mockImplementation(() => new Promise(() => {}));
+      
+      renderFailedDocumentViewer();
+      
+      expect(screen.getByRole('progressbar')).toBeInTheDocument();
+    });
+
+    test('should show loading spinner with correct styling', () => {
+      vi.mocked(api.get).mockImplementation(() => new Promise(() => {}));
+      
+      renderFailedDocumentViewer();
+      
+      const loadingContainer = screen.getByRole('progressbar').closest('div');
+      expect(loadingContainer).toHaveStyle({
+        display: 'flex',
+        justifyContent: 'center',
+        alignItems: 'center',
+        minHeight: '200px'
+      });
+    });
+  });
+
+  describe('Successful Document Loading', () => {
+    test('should load and display PDF document', async () => {
+      const mockResponse = {
+        data: new Blob(['mock pdf content'], { type: 'application/pdf' }),
+      };
+      vi.mocked(api.get).mockResolvedValueOnce(mockResponse);
+
+      renderFailedDocumentViewer();
+
+      await waitFor(() => {
+        expect(api.get).toHaveBeenCalledWith('/documents/failed/test-failed-doc-id/view', {
+          responseType: 'blob'
+        });
+      });
+
+      await waitFor(() => {
+        const iframe = screen.getByTitle('test-document.pdf');
+        expect(iframe).toBeInTheDocument();
+        expect(iframe).toHaveAttribute('src', 'mock-object-url');
+        expect(iframe).toHaveAttribute('width', '100%');
+        expect(iframe).toHaveAttribute('height', '400px');
+      });
+    });
+
+    test('should load and display image document', async () => {
+      const mockResponse = {
+        data: new Blob(['mock image content'], { type: 'image/jpeg' }),
+      };
+      vi.mocked(api.get).mockResolvedValueOnce(mockResponse);
+
+      renderFailedDocumentViewer({
+        filename: 'test-image.jpg',
+        mimeType: 'image/jpeg'
+      });
+
+      await waitFor(() => {
+        const image = screen.getByAltText('test-image.jpg');
+        expect(image).toBeInTheDocument();
+        expect(image).toHaveAttribute('src', 'mock-object-url');
+        expect(image).toHaveStyle({
+          maxWidth: '100%',
+          maxHeight: '400px',
+          objectFit: 'contain',
+        });
+      });
+    });
+
+    test('should load and display text document', async () => {
+      const mockResponse = {
+        data: new Blob(['mock text content'], { type: 'text/plain' }),
+      };
+      vi.mocked(api.get).mockResolvedValueOnce(mockResponse);
+
+      renderFailedDocumentViewer({
+        filename: 'test-file.txt',
+        mimeType: 'text/plain'
+      });
+
+      await waitFor(() => {
+        const iframe = screen.getByTitle('test-file.txt');
+        expect(iframe).toBeInTheDocument();
+        expect(iframe).toHaveAttribute('src', 'mock-object-url');
+      });
+    });
+
+    test('should show unsupported file type message', async () => {
+      const mockResponse = {
+        data: new Blob(['mock content'], { type: 'application/unknown' }),
+      };
+      vi.mocked(api.get).mockResolvedValueOnce(mockResponse);
+
+      renderFailedDocumentViewer({
+        filename: 'test-file.unknown',
+        mimeType: 'application/unknown'
+      });
+
+      await waitFor(() => {
+        expect(screen.getByText('Cannot preview this file type (application/unknown)')).toBeInTheDocument();
+        expect(screen.getByText('File: test-file.unknown')).toBeInTheDocument();
+        expect(screen.getByText('You can try downloading the file to view it locally.')).toBeInTheDocument();
+      });
+    });
+  });
+
+  describe('Error Handling', () => {
+    test('should show 404 error when document not found', async () => {
+      const error = {
+        response: { status: 404 }
+      };
+      vi.mocked(api.get).mockRejectedValueOnce(error);
+
+      renderFailedDocumentViewer();
+
+      await waitFor(() => {
+        expect(screen.getByText('Document file not found or has been deleted')).toBeInTheDocument();
+        expect(screen.getByText('The original file may have been deleted or moved from storage.')).toBeInTheDocument();
+      });
+    });
+
+    test('should show generic error for other failures', async () => {
+      const error = new Error('Network error');
+      vi.mocked(api.get).mockRejectedValueOnce(error);
+
+      renderFailedDocumentViewer();
+
+      await waitFor(() => {
+        expect(screen.getByText('Failed to load document for viewing')).toBeInTheDocument();
+        expect(screen.getByText('The original file may have been deleted or moved from storage.')).toBeInTheDocument();
+      });
+    });
+
+    test('should handle API errors gracefully', async () => {
+      const error = {
+        response: { status: 500 }
+      };
+      vi.mocked(api.get).mockRejectedValueOnce(error);
+
+      renderFailedDocumentViewer();
+
+      await waitFor(() => {
+        expect(screen.getByText('Failed to load document for viewing')).toBeInTheDocument();
+      });
+    });
+  });
+
+  describe('Memory Management', () => {
+    test('should create object URL when loading document', async () => {
+      const mockResponse = {
+        data: new Blob(['mock content'], { type: 'application/pdf' }),
+      };
+      vi.mocked(api.get).mockResolvedValueOnce(mockResponse);
+
+      renderFailedDocumentViewer();
+
+      await waitFor(() => {
+        expect(mockCreateObjectURL).toHaveBeenCalled();
+      });
+
+      // Should display the document
+      await waitFor(() => {
+        expect(screen.getByTitle(defaultProps.filename)).toBeInTheDocument();
+      });
+    });
+
+    test('should create new object URL when failedDocumentId changes', async () => {
+      const mockResponse = {
+        data: new Blob(['mock content'], { type: 'application/pdf' }),
+      };
+      vi.mocked(api.get).mockResolvedValue(mockResponse);
+
+      const { rerender } = renderFailedDocumentViewer();
+
+      await waitFor(() => {
+        expect(api.get).toHaveBeenCalledWith('/documents/failed/test-failed-doc-id/view', {
+          responseType: 'blob'
+        });
+      });
+
+      // Change the failedDocumentId
+      rerender(
+        <ThemeProvider theme={theme}>
+          <FailedDocumentViewer
+            failedDocumentId="new-doc-id"
+            filename="test-document.pdf"
+            mimeType="application/pdf"
+          />
+        </ThemeProvider>
+      );
+
+      await waitFor(() => {
+        expect(api.get).toHaveBeenCalledWith('/documents/failed/new-doc-id/view', {
+          responseType: 'blob'
+        });
+      });
+
+      expect(api.get).toHaveBeenCalledTimes(2);
+    });
+  });
+
+  describe('Document Types', () => {
+    test('should handle PDF documents correctly', async () => {
+      const mockResponse = {
+        data: new Blob(['mock pdf content'], { type: 'application/pdf' }),
+      };
+      vi.mocked(api.get).mockResolvedValueOnce(mockResponse);
+
+      renderFailedDocumentViewer({
+        mimeType: 'application/pdf'
+      });
+
+      await waitFor(() => {
+        const iframe = screen.getByTitle(defaultProps.filename);
+        expect(iframe).toBeInTheDocument();
+        expect(iframe.tagName).toBe('IFRAME');
+      });
+    });
+
+    test('should handle various image types', async () => {
+      const imageTypes = ['image/jpeg', 'image/png', 'image/gif', 'image/webp'];
+
+      for (const mimeType of imageTypes) {
+        const mockResponse = {
+          data: new Blob(['mock image content'], { type: mimeType }),
+        };
+        vi.mocked(api.get).mockResolvedValueOnce(mockResponse);
+
+        const filename = `test.${mimeType.split('/')[1]}`;
+        renderFailedDocumentViewer({
+          filename,
+          mimeType
+        });
+
+        await waitFor(() => {
+          const image = screen.getByAltText(filename);
+          expect(image).toBeInTheDocument();
+          expect(image.tagName).toBe('IMG');
+        });
+
+        // Clean up for next iteration
+        screen.getByAltText(filename).remove();
+      }
+    });
+
+    test('should handle text documents', async () => {
+      const textTypes = ['text/plain', 'text/html', 'text/css'];
+
+      for (const mimeType of textTypes) {
+        const mockResponse = {
+          data: new Blob(['mock text content'], { type: mimeType }),
+        };
+        vi.mocked(api.get).mockResolvedValueOnce(mockResponse);
+
+        const filename = `test.${mimeType.split('/')[1]}`;
+        renderFailedDocumentViewer({
+          filename,
+          mimeType
+        });
+
+        await waitFor(() => {
+          const iframe = screen.getByTitle(filename);
+          expect(iframe).toBeInTheDocument();
+          expect(iframe.tagName).toBe('IFRAME');
+        });
+
+        // Clean up for next iteration
+        screen.getByTitle(filename).remove();
+      }
+    });
+  });
+
+  describe('Styling and Layout', () => {
+    test('should apply correct Paper styling', async () => {
+      const mockResponse = {
+        data: new Blob(['mock content'], { type: 'application/pdf' }),
+      };
+      vi.mocked(api.get).mockResolvedValueOnce(mockResponse);
+
+      renderFailedDocumentViewer();
+
+      await waitFor(() => {
+        const paper = screen.getByTitle(defaultProps.filename).closest('.MuiPaper-root');
+        expect(paper).toHaveClass('MuiPaper-root');
+      });
+    });
+
+    test('should center images properly', async () => {
+      const mockResponse = {
+        data: new Blob(['mock image content'], { type: 'image/jpeg' }),
+      };
+      vi.mocked(api.get).mockResolvedValueOnce(mockResponse);
+
+      renderFailedDocumentViewer({
+        mimeType: 'image/jpeg'
+      });
+
+      await waitFor(() => {
+        const imageContainer = screen.getByAltText(defaultProps.filename).closest('div');
+        expect(imageContainer).toHaveStyle({
+          textAlign: 'center'
+        });
+      });
+    });
+  });
+
+  describe('API Call Parameters', () => {
+    test('should call API with correct endpoint and parameters', async () => {
+      const mockResponse = {
+        data: new Blob(['mock content'], { type: 'application/pdf' }),
+      };
+      vi.mocked(api.get).mockResolvedValueOnce(mockResponse);
+
+      renderFailedDocumentViewer();
+
+      await waitFor(() => {
+        expect(api.get).toHaveBeenCalledWith('/documents/failed/test-failed-doc-id/view', {
+          responseType: 'blob'
+        });
+      });
+    });
+
+    test('should handle different document IDs correctly', async () => {
+      const mockResponse = {
+        data: new Blob(['mock content'], { type: 'application/pdf' }),
+      };
+      vi.mocked(api.get).mockResolvedValueOnce(mockResponse);
+
+      renderFailedDocumentViewer({
+        failedDocumentId: 'different-doc-id'
+      });
+
+      await waitFor(() => {
+        expect(api.get).toHaveBeenCalledWith('/documents/failed/different-doc-id/view', {
+          responseType: 'blob'
+        });
+      });
+    });
+  });
+
+  describe('Edge Cases', () => {
+    test('should handle empty blob response', async () => {
+      const mockResponse = {
+        data: new Blob([], { type: 'application/pdf' }),
+      };
+      vi.mocked(api.get).mockResolvedValueOnce(mockResponse);
+
+      renderFailedDocumentViewer();
+
+      await waitFor(() => {
+        // Should still create object URL and show iframe
+        expect(mockCreateObjectURL).toHaveBeenCalled();
+        expect(screen.getByTitle(defaultProps.filename)).toBeInTheDocument();
+      });
+    });
+
+    test('should handle very long filenames', async () => {
+      const longFilename = 'a'.repeat(500) + '.pdf';
+      const mockResponse = {
+        data: new Blob(['mock content'], { type: 'application/pdf' }),
+      };
+      vi.mocked(api.get).mockResolvedValueOnce(mockResponse);
+
+      renderFailedDocumentViewer({
+        filename: longFilename
+      });
+
+      await waitFor(() => {
+        expect(screen.getByTitle(longFilename)).toBeInTheDocument();
+      });
+    });
+
+    test('should handle special characters in filename', async () => {
+      const specialFilename = 'test file & "quotes" <brackets>.pdf';
+      const mockResponse = {
+        data: new Blob(['mock content'], { type: 'application/pdf' }),
+      };
+      vi.mocked(api.get).mockResolvedValueOnce(mockResponse);
+
+      renderFailedDocumentViewer({
+        filename: specialFilename
+      });
+
+      await waitFor(() => {
+        expect(screen.getByTitle(specialFilename)).toBeInTheDocument();
+      });
+    });
+
+    test('should handle undefined or null mimeType gracefully', async () => {
+      const mockResponse = {
+        data: new Blob(['mock content'], { type: '' }),
+      };
+      vi.mocked(api.get).mockResolvedValueOnce(mockResponse);
+
+      renderFailedDocumentViewer({
+        mimeType: undefined as any
+      });
+
+      await waitFor(() => {
+        // Should show unsupported file type message
+        expect(screen.getByText(/Cannot preview this file type \(unknown\)/)).toBeInTheDocument();
+      });
+    });
+  });
+
+  describe('Accessibility', () => {
+    test('should have proper ARIA attributes', async () => {
+      const mockResponse = {
+        data: new Blob(['mock content'], { type: 'application/pdf' }),
+      };
+      vi.mocked(api.get).mockResolvedValueOnce(mockResponse);
+
+      renderFailedDocumentViewer();
+
+      await waitFor(() => {
+        const iframe = screen.getByTitle(defaultProps.filename);
+        expect(iframe).toHaveAttribute('title', defaultProps.filename);
+      });
+    });
+
+    test('should have proper alt text for images', async () => {
+      const mockResponse = {
+        data: new Blob(['mock image content'], { type: 'image/jpeg' }),
+      };
+      vi.mocked(api.get).mockResolvedValueOnce(mockResponse);
+
+      renderFailedDocumentViewer({
+        mimeType: 'image/jpeg'
+      });
+
+      await waitFor(() => {
+        const image = screen.getByAltText(defaultProps.filename);
+        expect(image).toBeInTheDocument();
+      });
+    });
+  });
+});
\ No newline at end of file
diff --git a/frontend/src/pages/DocumentManagementPage.tsx b/frontend/src/pages/DocumentManagementPage.tsx
index 7c865db..b8d6a53 100644
--- a/frontend/src/pages/DocumentManagementPage.tsx
+++ b/frontend/src/pages/DocumentManagementPage.tsx
@@ -1020,11 +1020,11 @@ const DocumentManagementPage: React.FC = () => {
                                 {/* Show OCR confidence and word count for low confidence failures */}
                                 {(document.failure_reason === 'low_ocr_confidence' || document.ocr_failure_reason === 'low_ocr_confidence') && (
                                   <>
-                                    <Typography variant="body2" color="text.secondary">
+                                    <Typography variant="body2" color="text.secondary" component="div">
                                       <strong>OCR Results:</strong>
                                     </Typography>
-                                    <Box sx={{ mb: 1, display: 'flex', gap: 2, flexWrap: 'wrap' }}>
-                                      {document.ocr_confidence !== undefined && (
+                                    <Box component="div" sx={{ mb: 1, display: 'flex', gap: 2, flexWrap: 'wrap' }}>
+                                      {document.ocr_confidence !== undefined && document.ocr_confidence !== null && (
                                         <Chip
                                           size="small"
                                           icon={<WarningIcon />}
@@ -1959,28 +1959,28 @@ const DocumentManagementPage: React.FC = () => {
                   Document Information
                 </Typography>
                 <Box>
-                  <Typography variant="body2" color="text.secondary">
+                  <Typography variant="body2" color="text.secondary" component="div">
                     <strong>Original Filename:</strong>
                   </Typography>
                   <Typography variant="body2" sx={{ mb: 2 }}>
                     {selectedDocument.original_filename}
                   </Typography>
 
-                  <Typography variant="body2" color="text.secondary">
+                  <Typography variant="body2" color="text.secondary" component="div">
                     <strong>File Size:</strong>
                   </Typography>
                   <Typography variant="body2" sx={{ mb: 2 }}>
                     {formatFileSize(selectedDocument.file_size)}
                   </Typography>
 
-                  <Typography variant="body2" color="text.secondary">
+                  <Typography variant="body2" color="text.secondary" component="div">
                     <strong>MIME Type:</strong>
                   </Typography>
                   <Typography variant="body2" sx={{ mb: 2 }}>
                     {selectedDocument.mime_type}
                   </Typography>
 
-                  <Typography variant="body2" color="text.secondary">
+                  <Typography variant="body2" color="text.secondary" component="div">
                     <strong>Failure Category:</strong>
                   </Typography>
                   <Chip
@@ -1989,21 +1989,21 @@ const DocumentManagementPage: React.FC = () => {
                     sx={{ mb: 2 }}
                   />
 
-                  <Typography variant="body2" color="text.secondary" sx={{ mt: 2 }}>
+                  <Typography variant="body2" color="text.secondary" component="div" sx={{ mt: 2 }}>
                     <strong>Retry Count:</strong>
                   </Typography>
                   <Typography variant="body2" sx={{ mb: 2 }}>
                     {selectedDocument.retry_count} attempts
                   </Typography>
 
-                  <Typography variant="body2" color="text.secondary">
+                  <Typography variant="body2" color="text.secondary" component="div">
                     <strong>Created:</strong>
                   </Typography>
                   <Typography variant="body2" sx={{ mb: 2 }}>
                     {format(new Date(selectedDocument.created_at), 'PPpp')}
                   </Typography>
 
-                  <Typography variant="body2" color="text.secondary">
+                  <Typography variant="body2" color="text.secondary" component="div">
                     <strong>Last Updated:</strong>
                   </Typography>
                   <Typography variant="body2">
@@ -2013,13 +2013,13 @@ const DocumentManagementPage: React.FC = () => {
                   <Typography variant="body2" color="text.secondary" sx={{ mt: 2 }}>
                     <strong>Tags:</strong>
                   </Typography>
-                  <Box sx={{ mb: 2 }}>
+                  <Box component="div" sx={{ mb: 2 }}>
                     {selectedDocument.tags.length > 0 ? (
                       selectedDocument.tags.map((tag) => (
                         <Chip key={tag} label={tag} size="small" sx={{ mr: 1, mb: 1 }} />
                       ))
                     ) : (
-                      <Typography variant="body2" color="text.secondary">No tags</Typography>
+                      <Typography variant="body2" color="text.secondary" component="span">No tags</Typography>
                     )}
                   </Box>
                 </Box>
@@ -2031,7 +2031,7 @@ const DocumentManagementPage: React.FC = () => {
                 <Typography variant="h6" sx={{ mb: 2 }}>
                   Error Details
                 </Typography>
-                <Typography variant="body2" color="text.secondary" sx={{ mb: 1 }}>
+                <Typography variant="body2" color="text.secondary" component="div" sx={{ mb: 1 }}>
                   <strong>Full Error Message:</strong>
                 </Typography>
                 <Paper sx={{ 
diff --git a/frontend/src/pages/__tests__/DocumentManagementPage.runtime-errors.test.tsx b/frontend/src/pages/__tests__/DocumentManagementPage.runtime-errors.test.tsx
new file mode 100644
index 0000000..594b924
--- /dev/null
+++ b/frontend/src/pages/__tests__/DocumentManagementPage.runtime-errors.test.tsx
@@ -0,0 +1,600 @@
+import { describe, test, expect, vi, beforeEach } from 'vitest';
+import { render, screen, waitFor, fireEvent } from '@testing-library/react';
+import { BrowserRouter } from 'react-router-dom';
+import { ThemeProvider, createTheme } from '@mui/material/styles';
+import DocumentManagementPage from '../DocumentManagementPage';
+import userEvent from '@testing-library/user-event';
+
+// Mock API with comprehensive responses
+vi.mock('../../services/api', () => ({
+  api: {
+    get: vi.fn(),
+    delete: vi.fn(),
+  },
+  documentService: {
+    getFailedDocuments: vi.fn(),
+    getFailedOcrDocuments: vi.fn(),
+    getDuplicates: vi.fn(),
+    retryOcr: vi.fn(),
+    deleteLowConfidence: vi.fn(),
+    deleteFailedOcr: vi.fn(),
+    downloadFile: vi.fn(),
+  },
+  queueService: {
+    requeueFailed: vi.fn(),
+  },
+}));
+
+const theme = createTheme();
+
+const DocumentManagementPageWrapper = ({ children }: { children: React.ReactNode }) => {
+  return (
+    <BrowserRouter>
+      <ThemeProvider theme={theme}>
+        {children}
+      </ThemeProvider>
+    </BrowserRouter>
+  );
+};
+
+describe('DocumentManagementPage - Runtime Error Prevention', () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+  });
+
+  describe('OCR Confidence Display - Null Safety', () => {
+    test('should handle null ocr_confidence without crashing', async () => {
+      const mockFailedDocument = {
+        id: 'test-doc-1',
+        filename: 'test.pdf',
+        original_filename: 'test.pdf',
+        file_size: 1024,
+        mime_type: 'application/pdf',
+        created_at: '2024-01-01T00:00:00Z',
+        updated_at: '2024-01-01T00:00:00Z',
+        tags: [],
+        failure_reason: 'low_ocr_confidence',
+        failure_category: 'OCR Error',
+        retry_count: 0,
+        can_retry: true,
+        ocr_confidence: null, // This should not cause a crash
+        ocr_word_count: 10,
+        error_message: 'Low confidence OCR result',
+      };
+
+      // Mock the API service
+      const { documentService } = await import('../../services/api');
+      vi.mocked(documentService.getFailedDocuments).mockResolvedValueOnce({
+        data: {
+          documents: [mockFailedDocument],
+          pagination: { total: 1, limit: 25, offset: 0, total_pages: 1 },
+          statistics: { total_failed: 1, by_reason: {}, by_stage: {} },
+        },
+      });
+
+      render(
+        <DocumentManagementPageWrapper>
+          <DocumentManagementPage />
+        </DocumentManagementPageWrapper>
+      );
+
+      // Wait for data to load
+      await waitFor(() => {
+        expect(screen.getByText('test.pdf')).toBeInTheDocument();
+      });
+
+      // Expand the row to see details
+      const expandButton = screen.getByLabelText(/expand/i) || screen.getAllByRole('button')[0];
+      fireEvent.click(expandButton);
+
+      // Should not show confidence chip since ocr_confidence is null
+      await waitFor(() => {
+        expect(screen.queryByText(/confidence/)).not.toBeInTheDocument();
+      });
+
+      // But should show word count if available
+      if (mockFailedDocument.ocr_word_count) {
+        expect(screen.getByText(/10 words found/)).toBeInTheDocument();
+      }
+    });
+
+    test('should handle undefined ocr_confidence without crashing', async () => {
+      const mockFailedDocument = {
+        id: 'test-doc-2',
+        filename: 'test2.pdf',
+        original_filename: 'test2.pdf',
+        file_size: 1024,
+        mime_type: 'application/pdf',
+        created_at: '2024-01-01T00:00:00Z',
+        updated_at: '2024-01-01T00:00:00Z',
+        tags: [],
+        failure_reason: 'low_ocr_confidence',
+        failure_category: 'OCR Error',
+        retry_count: 0,
+        can_retry: true,
+        // ocr_confidence is undefined
+        ocr_word_count: undefined,
+        error_message: 'Low confidence OCR result',
+      };
+
+      const { documentService } = await import('../../services/api');
+      vi.mocked(documentService.getFailedDocuments).mockResolvedValueOnce({
+        data: {
+          documents: [mockFailedDocument],
+          pagination: { total: 1, limit: 25, offset: 0, total_pages: 1 },
+          statistics: { total_failed: 1, by_reason: {}, by_stage: {} },
+        },
+      });
+
+      render(
+        <DocumentManagementPageWrapper>
+          <DocumentManagementPage />
+        </DocumentManagementPageWrapper>
+      );
+
+      await waitFor(() => {
+        expect(screen.getByText('test2.pdf')).toBeInTheDocument();
+      });
+
+      // Should render without crashing
+      expect(screen.getByText('Document Management')).toBeInTheDocument();
+    });
+
+    test('should properly display valid ocr_confidence values', async () => {
+      const mockFailedDocument = {
+        id: 'test-doc-3',
+        filename: 'test3.pdf',
+        original_filename: 'test3.pdf',
+        file_size: 1024,
+        mime_type: 'application/pdf',
+        created_at: '2024-01-01T00:00:00Z',
+        updated_at: '2024-01-01T00:00:00Z',
+        tags: [],
+        failure_reason: 'low_ocr_confidence',
+        failure_category: 'OCR Error',
+        retry_count: 0,
+        can_retry: true,
+        ocr_confidence: 15.7, // Valid number
+        ocr_word_count: 42,
+        error_message: 'Low confidence OCR result',
+      };
+
+      const { documentService } = await import('../../services/api');
+      vi.mocked(documentService.getFailedDocuments).mockResolvedValueOnce({
+        data: {
+          documents: [mockFailedDocument],
+          pagination: { total: 1, limit: 25, offset: 0, total_pages: 1 },
+          statistics: { total_failed: 1, by_reason: {}, by_stage: {} },
+        },
+      });
+
+      render(
+        <DocumentManagementPageWrapper>
+          <DocumentManagementPage />
+        </DocumentManagementPageWrapper>
+      );
+
+      await waitFor(() => {
+        expect(screen.getByText('test3.pdf')).toBeInTheDocument();
+      });
+
+      // Expand the row to see details
+      const expandButton = screen.getByLabelText(/expand/i) || screen.getAllByRole('button')[0];
+      fireEvent.click(expandButton);
+
+      // Should show confidence with proper formatting
+      await waitFor(() => {
+        expect(screen.getByText('15.7% confidence')).toBeInTheDocument();
+        expect(screen.getByText('42 words found')).toBeInTheDocument();
+      });
+    });
+  });
+
+  describe('HTML Structure Validation', () => {
+    test('should not nest block elements inside Typography components', async () => {
+      const mockFailedDocument = {
+        id: 'test-doc-4',
+        filename: 'test4.pdf',
+        original_filename: 'test4.pdf',
+        file_size: 1024,
+        mime_type: 'application/pdf',
+        created_at: '2024-01-01T00:00:00Z',
+        updated_at: '2024-01-01T00:00:00Z',
+        tags: ['tag1', 'tag2'],
+        failure_reason: 'low_ocr_confidence',
+        failure_category: 'OCR Error',
+        retry_count: 0,
+        can_retry: true,
+        ocr_confidence: 25.5,
+        ocr_word_count: 15,
+        error_message: 'Test error message',
+      };
+
+      const { documentService } = await import('../../services/api');
+      vi.mocked(documentService.getFailedDocuments).mockResolvedValueOnce({
+        data: {
+          documents: [mockFailedDocument],
+          pagination: { total: 1, limit: 25, offset: 0, total_pages: 1 },
+          statistics: { total_failed: 1, by_reason: {}, by_stage: {} },
+        },
+      });
+
+      render(
+        <DocumentManagementPageWrapper>
+          <DocumentManagementPage />
+        </DocumentManagementPageWrapper>
+      );
+
+      await waitFor(() => {
+        expect(screen.getByText('test4.pdf')).toBeInTheDocument();
+      });
+
+      // Click "View Details" to open the dialog
+      const viewButton = screen.getByLabelText(/view details/i) || screen.getByText(/view details/i);
+      fireEvent.click(viewButton);
+
+      await waitFor(() => {
+        expect(screen.getByText('Document Details: test4.pdf')).toBeInTheDocument();
+      });
+
+      // Check that tags are displayed correctly without HTML structure issues
+      expect(screen.getByText('tag1')).toBeInTheDocument();
+      expect(screen.getByText('tag2')).toBeInTheDocument();
+
+      // Check that all sections render without throwing HTML validation errors
+      expect(screen.getByText('Original Filename:')).toBeInTheDocument();
+      expect(screen.getByText('File Size:')).toBeInTheDocument();
+      expect(screen.getByText('MIME Type:')).toBeInTheDocument();
+      expect(screen.getByText('Full Error Message:')).toBeInTheDocument();
+    });
+  });
+
+  describe('Error Data Field Access', () => {
+    test('should handle missing error_message field gracefully', async () => {
+      const mockFailedDocument = {
+        id: 'test-doc-5',
+        filename: 'test5.pdf',
+        original_filename: 'test5.pdf',
+        file_size: 1024,
+        mime_type: 'application/pdf',
+        created_at: '2024-01-01T00:00:00Z',
+        updated_at: '2024-01-01T00:00:00Z',
+        tags: [],
+        failure_reason: 'processing_error',
+        failure_category: 'Processing Error',
+        retry_count: 0,
+        can_retry: true,
+        // error_message is missing
+        // ocr_error is missing too
+      };
+
+      const { documentService } = await import('../../services/api');
+      vi.mocked(documentService.getFailedDocuments).mockResolvedValueOnce({
+        data: {
+          documents: [mockFailedDocument],
+          pagination: { total: 1, limit: 25, offset: 0, total_pages: 1 },
+          statistics: { total_failed: 1, by_reason: {}, by_stage: {} },
+        },
+      });
+
+      render(
+        <DocumentManagementPageWrapper>
+          <DocumentManagementPage />
+        </DocumentManagementPageWrapper>
+      );
+
+      await waitFor(() => {
+        expect(screen.getByText('test5.pdf')).toBeInTheDocument();
+      });
+
+      // Expand the row to see details
+      const expandButton = screen.getByLabelText(/expand/i) || screen.getAllByRole('button')[0];
+      fireEvent.click(expandButton);
+
+      // Should show fallback text
+      await waitFor(() => {
+        expect(screen.getByText('No error message available')).toBeInTheDocument();
+      });
+    });
+
+    test('should prioritize error_message over ocr_error', async () => {
+      const mockFailedDocument = {
+        id: 'test-doc-6',
+        filename: 'test6.pdf',
+        original_filename: 'test6.pdf',
+        file_size: 1024,
+        mime_type: 'application/pdf',
+        created_at: '2024-01-01T00:00:00Z',
+        updated_at: '2024-01-01T00:00:00Z',
+        tags: [],
+        failure_reason: 'processing_error',
+        failure_category: 'Processing Error',
+        retry_count: 0,
+        can_retry: true,
+        error_message: 'New error message format',
+        ocr_error: 'Old OCR error format',
+      };
+
+      const { documentService } = await import('../../services/api');
+      vi.mocked(documentService.getFailedDocuments).mockResolvedValueOnce({
+        data: {
+          documents: [mockFailedDocument],
+          pagination: { total: 1, limit: 25, offset: 0, total_pages: 1 },
+          statistics: { total_failed: 1, by_reason: {}, by_stage: {} },
+        },
+      });
+
+      render(
+        <DocumentManagementPageWrapper>
+          <DocumentManagementPage />
+        </DocumentManagementPageWrapper>
+      );
+
+      await waitFor(() => {
+        expect(screen.getByText('test6.pdf')).toBeInTheDocument();
+      });
+
+      // Expand the row to see details
+      const expandButton = screen.getByLabelText(/expand/i) || screen.getAllByRole('button')[0];
+      fireEvent.click(expandButton);
+
+      // Should show the new error_message format, not ocr_error
+      await waitFor(() => {
+        expect(screen.getByText('New error message format')).toBeInTheDocument();
+        expect(screen.queryByText('Old OCR error format')).not.toBeInTheDocument();
+      });
+    });
+
+    test('should fallback to ocr_error when error_message is missing', async () => {
+      const mockFailedDocument = {
+        id: 'test-doc-7',
+        filename: 'test7.pdf',
+        original_filename: 'test7.pdf',
+        file_size: 1024,
+        mime_type: 'application/pdf',
+        created_at: '2024-01-01T00:00:00Z',
+        updated_at: '2024-01-01T00:00:00Z',
+        tags: [],
+        failure_reason: 'ocr_error',
+        failure_category: 'OCR Error',
+        retry_count: 0,
+        can_retry: true,
+        ocr_error: 'OCR processing failed',
+        // error_message is missing
+      };
+
+      const { documentService } = await import('../../services/api');
+      vi.mocked(documentService.getFailedDocuments).mockResolvedValueOnce({
+        data: {
+          documents: [mockFailedDocument],
+          pagination: { total: 1, limit: 25, offset: 0, total_pages: 1 },
+          statistics: { total_failed: 1, by_reason: {}, by_stage: {} },
+        },
+      });
+
+      render(
+        <DocumentManagementPageWrapper>
+          <DocumentManagementPage />
+        </DocumentManagementPageWrapper>
+      );
+
+      await waitFor(() => {
+        expect(screen.getByText('test7.pdf')).toBeInTheDocument();
+      });
+
+      // Expand the row to see details
+      const expandButton = screen.getByLabelText(/expand/i) || screen.getAllByRole('button')[0];
+      fireEvent.click(expandButton);
+
+      // Should show the OCR error
+      await waitFor(() => {
+        expect(screen.getByText('OCR processing failed')).toBeInTheDocument();
+      });
+    });
+  });
+
+  describe('Ignored Files Tab Functionality', () => {
+    test('should render ignored files tab without errors', async () => {
+      // Mock ignored files API responses
+      const { api } = await import('../../services/api');
+      vi.mocked(api.get).mockImplementation((url) => {
+        if (url.includes('/ignored-files/stats')) {
+          return Promise.resolve({
+            data: {
+              total_ignored_files: 5,
+              total_size_bytes: 1024000,
+              most_recent_ignored_at: '2024-01-01T00:00:00Z',
+            }
+          });
+        }
+        if (url.includes('/ignored-files')) {
+          return Promise.resolve({
+            data: {
+              ignored_files: [],
+              total: 0,
+            }
+          });
+        }
+        return Promise.resolve({ data: {} });
+      });
+
+      const { documentService } = await import('../../services/api');
+      vi.mocked(documentService.getFailedDocuments).mockResolvedValueOnce({
+        data: {
+          documents: [],
+          pagination: { total: 0, limit: 25, offset: 0, total_pages: 1 },
+          statistics: { total_failed: 0, by_reason: {}, by_stage: {} },
+        },
+      });
+
+      render(
+        <DocumentManagementPageWrapper>
+          <DocumentManagementPage />
+        </DocumentManagementPageWrapper>
+      );
+
+      await waitFor(() => {
+        expect(screen.getByText('Document Management')).toBeInTheDocument();
+      });
+
+      // Click on the Ignored Files tab
+      const ignoredFilesTab = screen.getByText(/Ignored Files/);
+      fireEvent.click(ignoredFilesTab);
+
+      // Should render without errors
+      await waitFor(() => {
+        expect(screen.getByText('Ignored Files Management')).toBeInTheDocument();
+      });
+    });
+  });
+
+  describe('Edge Cases and Boundary Conditions', () => {
+    test('should handle empty arrays and null values', async () => {
+      const mockFailedDocument = {
+        id: 'test-doc-8',
+        filename: 'test8.pdf',
+        original_filename: 'test8.pdf',
+        file_size: 0, // Edge case: zero file size
+        mime_type: 'application/pdf',
+        created_at: '2024-01-01T00:00:00Z',
+        updated_at: '2024-01-01T00:00:00Z',
+        tags: [], // Empty array
+        failure_reason: 'unknown',
+        failure_category: 'Unknown',
+        retry_count: 0,
+        can_retry: false,
+        ocr_confidence: 0, // Edge case: zero confidence
+        ocr_word_count: 0, // Edge case: zero words
+        error_message: '',
+      };
+
+      const { documentService } = await import('../../services/api');
+      vi.mocked(documentService.getFailedDocuments).mockResolvedValueOnce({
+        data: {
+          documents: [mockFailedDocument],
+          pagination: { total: 1, limit: 25, offset: 0, total_pages: 1 },
+          statistics: { total_failed: 1, by_reason: {}, by_stage: {} },
+        },
+      });
+
+      render(
+        <DocumentManagementPageWrapper>
+          <DocumentManagementPage />
+        </DocumentManagementPageWrapper>
+      );
+
+      await waitFor(() => {
+        expect(screen.getByText('test8.pdf')).toBeInTheDocument();
+      });
+
+      // Should render without crashing even with edge case values
+      expect(screen.getByText('Document Management')).toBeInTheDocument();
+    });
+
+    test('should handle very large numbers without crashing', async () => {
+      const mockFailedDocument = {
+        id: 'test-doc-9',
+        filename: 'test9.pdf',
+        original_filename: 'test9.pdf',
+        file_size: Number.MAX_SAFE_INTEGER, // Very large number
+        mime_type: 'application/pdf',
+        created_at: '2024-01-01T00:00:00Z',
+        updated_at: '2024-01-01T00:00:00Z',
+        tags: [],
+        failure_reason: 'low_ocr_confidence',
+        failure_category: 'OCR Error',
+        retry_count: 999,
+        can_retry: true,
+        ocr_confidence: 99.999999, // High precision number
+        ocr_word_count: 1000000, // Large word count
+        error_message: 'Test error',
+      };
+
+      const { documentService } = await import('../../services/api');
+      vi.mocked(documentService.getFailedDocuments).mockResolvedValueOnce({
+        data: {
+          documents: [mockFailedDocument],
+          pagination: { total: 1, limit: 25, offset: 0, total_pages: 1 },
+          statistics: { total_failed: 1, by_reason: {}, by_stage: {} },
+        },
+      });
+
+      render(
+        <DocumentManagementPageWrapper>
+          <DocumentManagementPage />
+        </DocumentManagementPageWrapper>
+      );
+
+      await waitFor(() => {
+        expect(screen.getByText('test9.pdf')).toBeInTheDocument();
+      });
+
+      // Expand the row to see details
+      const expandButton = screen.getByLabelText(/expand/i) || screen.getAllByRole('button')[0];
+      fireEvent.click(expandButton);
+
+      // Should handle large numbers gracefully
+      await waitFor(() => {
+        expect(screen.getByText('100.0% confidence')).toBeInTheDocument(); // Should be rounded properly
+        expect(screen.getByText('1000000 words found')).toBeInTheDocument();
+      });
+    });
+  });
+
+  describe('Component Lifecycle and State Management', () => {
+    test('should handle rapid tab switching without errors', async () => {
+      const { documentService } = await import('../../services/api');
+      const { api } = await import('../../services/api');
+      
+      // Mock all necessary API calls
+      vi.mocked(documentService.getFailedDocuments).mockResolvedValue({
+        data: {
+          documents: [],
+          pagination: { total: 0, limit: 25, offset: 0, total_pages: 1 },
+          statistics: { total_failed: 0, by_reason: {}, by_stage: {} },
+        },
+      });
+
+      vi.mocked(documentService.getDuplicates).mockResolvedValue({
+        data: {
+          duplicates: [],
+          pagination: { total: 0, limit: 25, offset: 0, has_more: false },
+          statistics: { total_duplicate_groups: 0 },
+        },
+      });
+
+      vi.mocked(api.get).mockResolvedValue({
+        data: {
+          ignored_files: [],
+          total: 0,
+        }
+      });
+
+      const user = userEvent.setup();
+
+      render(
+        <DocumentManagementPageWrapper>
+          <DocumentManagementPage />
+        </DocumentManagementPageWrapper>
+      );
+
+      await waitFor(() => {
+        expect(screen.getByText('Document Management')).toBeInTheDocument();
+      });
+
+      // Rapidly switch between tabs
+      const tabs = screen.getAllByRole('tab');
+      
+      for (let i = 0; i < tabs.length; i++) {
+        await user.click(tabs[i]);
+        // Wait a minimal amount to ensure state updates
+        await waitFor(() => {
+          expect(tabs[i]).toHaveAttribute('aria-selected', 'true');
+        });
+      }
+
+      // Should not crash or throw errors
+      expect(screen.getByText('Document Management')).toBeInTheDocument();
+    });
+  });
+});
\ No newline at end of file