catch openai rate limit error (#7658)

api/services/app_generate_service.py

@@ -1,6 +1,8 @@
 from collections.abc import Generator
 from typing import Any, Union
 
+from openai._exceptions import RateLimitError
+
 from configs import dify_config
 from core.app.apps.advanced_chat.app_generator import AdvancedChatAppGenerator
 from core.app.apps.agent_chat.app_generator import AgentChatAppGenerator
@@ -10,6 +12,7 @@ from core.app.apps.workflow.app_generator import WorkflowAppGenerator
 from core.app.entities.app_invoke_entities import InvokeFrom
 from core.app.features.rate_limiting import RateLimit
 from models.model import Account, App, AppMode, EndUser
+from services.errors.llm import InvokeRateLimitError
 from services.workflow_service import WorkflowService
 
 
@@ -86,6 +89,8 @@ class AppGenerateService:
                 )
             else:
                 raise ValueError(f"Invalid app mode {app_model.mode}")
+        except RateLimitError as e:
+            raise InvokeRateLimitError(str(e))
         finally:
             if not streaming:
                 rate_limit.exit(request_id)