Show relevant error in UI (#2516)

opendevin/controller/agent_controller.py

@@ -120,9 +120,9 @@ class AgentController:
         - the string message should be user-friendly, it will be shown in the UI
         - an ErrorObservation can be sent to the LLM by the agent, with the exception message, so it can self-correct next time
         """
-        self.state.error = message
         if exception:
-            self.state.error += f': {str(exception)}'
+            message += f': {exception}'
+        self.state.error = message
         await self.event_stream.add_event(ErrorObservation(message), EventSource.AGENT)
 
     async def add_history(self, action: Action, observation: Observation):
@@ -140,7 +140,6 @@ class AgentController:
                 logger.info('AgentController task was cancelled')
                 break
             except Exception as e:
-                traceback.print_exc()
                 logger.error(f'Error while running the agent: {e}')
                 logger.error(traceback.format_exc())
                 await self.report_error(