fix: add validity check for multilingual

app.py

@@ -655,6 +655,11 @@ def generate_image_multilingual(bg_prompt, bg_class, bg_tags, seed, cfg, *condit
     langs = []
     bboxes = []
     num_boxes = len(stack_cp) if len(stack_cp[-1]) == 4 else len(stack_cp) - 1
+
+    for i in range(num_boxes):
+        if conditions[i + MAX_TEXT_BOX * 2] is None:
+            raise gr.Error(f"Invalid conditions for box {i + 1} !")
+    
     for i in range(num_boxes):
         prompts.append(conditions[i])
         colors.append(conditions[i + MAX_TEXT_BOX])