Update app.py

app.py

@@ -458,11 +458,15 @@ HTML_CONTENT = """
         }
 
         function handleFileSelect(e) {
-            if (e.target.files.length > 0) {
+            if (e.target.files && e.target.files.length > 0) {
                 const file = e.target.files[0];
                 fileName.textContent = file.name;
                 uploadBtn.style.display = 'inline-block';
-                fileInput.files = e.target.files;  // Update the fileInput with the new file
+                
+                // Create a new FileList containing only the selected file
+                const dataTransfer = new DataTransfer();
+                dataTransfer.items.add(file);
+                fileInput.files = dataTransfer.files;
             }
         }