Add better error handling for model loading and directory creation

app.py

@@ -334,8 +334,12 @@ def process_file_background(task_id: str, file_data: bytes, filename: str, extra
         include_images = extraction_mode != 'markdown'
         include_markdown = extraction_mode != 'images'
         
+        # Ensure upload directory exists
+        upload_dir = Path(app.config['UPLOAD_FOLDER'])
+        upload_dir.mkdir(parents=True, exist_ok=True)
+        
         # Save uploaded file from bytes data
-        upload_path = Path(app.config['UPLOAD_FOLDER']) / filename
+        upload_path = upload_dir / filename
         upload_path.write_bytes(file_data)
         
         _update_task_progress(task_id, filename, 15, f'Saved {filename}, preparing output...')
@@ -355,7 +359,14 @@ def process_file_background(task_id: str, file_data: bytes, filename: str, extra
         logger.info(f"Processing {filename} (images={include_images}, markdown={include_markdown})")
         
         if include_images:
-            load_model_once()
+            try:
+                load_model_once()
+                logger.info(f"Model loaded successfully for {filename}")
+            except Exception as model_error:
+                logger.error(f"Failed to load model for {filename}: {model_error}")
+                import traceback
+                logger.error(traceback.format_exc())
+                raise Exception(f"Model loading failed: {str(model_error)}. The processing service may be unavailable.")
         
         _update_task_progress(task_id, filename, 30, f'Extracting content from {filename}...')