Update app.py

app.py

@@ -15,6 +15,13 @@ def read_image(image):
 
 @spaces.GPU(duration=180)
 def process_images(chapter_pages, character_bank_images, character_bank_names):
+    if chapter_pages is None:
+        return [], ""
+    if character_bank_images is None:
+        character_bank_images = []
+        character_bank_names = "" 
+    if character_bank_names is None or character_bank_names == "":
+        character_bank_names = ",".join([os.path.splitext(os.path.basename(x))[0] for x in character_bank_images])
     chapter_pages = [read_image(image) for image in chapter_pages]
     character_bank = {
         "images": [read_image(image) for image in character_bank_images],