make sure to raise exception if redis is not there (#674)

### What problem does this PR solve?

### Type of change

- [x] Refactoring

api/apps/llm_app.py

     return get_json_result(data=True)
 
 
+@manager.route('/delete_llm', methods=['POST'])
+@login_required
+@validate_request("llm_factory", "llm_name")
+def delete_llm():
+    req = request.json
+    TenantLLMService.filter_delete(
+            [TenantLLM.tenant_id == current_user.id, TenantLLM.llm_factory == req["llm_factory"], TenantLLM.llm_name == req["llm_name"]])
+    return get_json_result(data=True)
+
+
 @manager.route('/my_llms', methods=['GET'])
 @login_required
 def my_llms():

api/db/services/task_service.py

     DocumentService.begin2parse(doc["id"])
 
     for t in tsks:
-        REDIS_CONN.queue_product(SVR_QUEUE_NAME, message=t)
+        assert REDIS_CONN.queue_product(SVR_QUEUE_NAME, message=t), "Can't access Redis. Please check the Redis' status."