Update app.py

app.py

@@ -77,14 +77,15 @@ def process_zip_files(zip_file_paths):
     return csv_file_path
 
 def gr_process(zip_files, image_files):
-    if zip_files:
+    if not zip_files and not image_files:
+        raise ValueError("At least one of zip_files or image_files must be provided.")
+    elif zip_files:
         zip_file_paths = [zip_file.name for zip_file in zip_files]
         return process_zip_files(zip_file_paths)
     elif image_files:
         image_file_paths = [image_file.name for image_file in image_files]
         return process_images(image_file_paths)
-    else:
-        return None
+
 def combine_csv_files(file1, file2, output_file='combined_captions.csv'):
     with open(output_file, mode='w', newline='') as outfile:
         writer = csv.writer(outfile)