better visible error message

app.py

@@ -822,7 +822,20 @@ with gr.Blocks(theme=gr.themes.Soft()) as demo:
                 self.returncode = None
 
             def run(self):
-                self.returncode = run_autoforge_process(self.cmd, self.log_path)
+                try:
+                    self.returncode = run_autoforge_process(self.cmd, self.log_path)
+                except Exception as e:
+                    self.exc = e
+                    capture_exception(e)  # still goes to Sentry
+                    # make the error visible in the UI console
+                    with open(self.log_path, "a", encoding="utf-8") as lf:
+                        lf.write(
+                            "\nERROR: {}. This usually means the space has no free GPU "
+                            "minutes left right now. Please clone the docker container, run it locally or wait for a bit.\n".format(e)
+                        )
+                    # a non-zero code tells the outer loop something went wrong
+                    self.returncode = -1
+
 
         worker = Worker(command, log_file)
         worker.start()
@@ -970,4 +983,4 @@ if __name__ == "__main__":
         except Exception as e:
             print(f"Could not write default {DEFAULT_MATERIALS_CSV}: {e}")
     print("To run the UI, execute: python app.py")  # Corrected to python app.py
-    demo.queue(default_concurrency_limit=4).launch(share=False)
+    demo.queue(default_concurrency_limit=1).launch(share=False)