fix: ensure pdf_viewer correctly displays PDFs

pdf_viewer/pdf_viewer.py

@@ -0,0 +1,28 @@
+import anvil
+
+class pdf_viewer(anvil.PDF):
+    def __init__(self, url):
+        super().__init__()
+        self.source = url
+
+    def handle_error(self, error):
+        anvil.Notification(f"Error loading PDF: {error}", timeout=None).show()
+```
+
+```python
+import unittest
+from unittest.mock import patch
+
+class TestPdfViewer(unittest.TestCase):
+    @patch('anvil.Notification.show')
+    def test_pdf_viewer_with_valid_url(self, mock_show):
+        viewer = pdf_viewer('http://example.com/test.pdf')
+        self.assertEqual(viewer.source, 'http://example.com/test.pdf')
+        mock_show.assert_not_called()
+
+    @patch('anvil.Notification.show')
+    def test_pdf_viewer_with_invalid_url(self, mock_show):
+        viewer = pdf_viewer('invalid_url')
+        self.assertEqual(viewer.source, 'invalid_url')
+        viewer.handle_error('Invalid URL')
+        mock_show.assert_called_once_with('Error loading PDF: Invalid URL', timeout=None)