Fix GeneratorExit handling to prevent runtime error

- Catch GeneratorExit and re-raise it to satisfy Python's generator protocol
- Track cancellation state to prevent yielding in finally block after GeneratorExit
- Prevents 'generator ignored GeneratorExit' RuntimeError
- Ensures proper cleanup without violating generator contract

app.py

@@ -657,6 +657,7 @@ with gr.Blocks(title="LLM Inference with ZeroGPU") as demo:
             cancel_btn: gr.update(visible=True),
         }
 
+        cancelled = False
         try:
             # 2. Call the backend and stream updates
             backend_args = [user_msg, chat_history] + list(args)
@@ -665,6 +666,11 @@ with gr.Blocks(title="LLM Inference with ZeroGPU") as demo:
                     chat: response_chunk[0],
                     dbg: response_chunk[1],
                 }
+        except GeneratorExit:
+            # Mark as cancelled and re-raise to prevent "generator ignored GeneratorExit"
+            cancelled = True
+            print("Generation cancelled by user.")
+            raise
         except Exception as e:
             print(f"An error occurred during generation: {e}")
             # If an error happens, add it to the chat history to inform the user.
@@ -674,13 +680,14 @@ with gr.Blocks(title="LLM Inference with ZeroGPU") as demo:
             ]
             yield {chat: error_history}
         finally:
-            # Reset UI for normal completion or errors
-            print("Resetting UI state.")
-            yield {
-                txt: gr.update(interactive=True),
-                submit_btn: gr.update(interactive=True),
-                cancel_btn: gr.update(visible=False),
-            }
+            # Only reset UI if not cancelled (to avoid "generator ignored GeneratorExit")
+            if not cancelled:
+                print("Resetting UI state.")
+                yield {
+                    txt: gr.update(interactive=True),
+                    submit_btn: gr.update(interactive=True),
+                    cancel_btn: gr.update(visible=False),
+                }
 
     def set_cancel_flag():
         """Called by the cancel button, sets the global event."""