Surface ZeroGPU worker traceback via try/except for diagnosis

app.py

@@ -126,8 +126,7 @@ def clean(text: str) -> str:
     return text.rstrip()
 
 
-@gpu(duration=120)
-def complete(code, temperature, max_tokens, top_p):
+def _complete_impl(code, temperature, max_tokens, top_p):
     if code.strip() == "":
         return "", code, "*Empty input.*"
     if CURSOR in code:
@@ -169,6 +168,15 @@ def complete(code, temperature, max_tokens, top_p):
     return text, assembled, stats
 
 
+@gpu(duration=120)
+def complete(code, temperature, max_tokens, top_p):
+    import traceback
+    try:
+        return _complete_impl(code, temperature, max_tokens, top_p)
+    except Exception:
+        return "", code, "```\n" + traceback.format_exc() + "\n```"
+
+
 with gr.Blocks(title="RustLean FIM Playground") as demo:
     gr.Markdown(
         "# 🦀 RustLean — Rust FIM Completion\n"