[Vue warn]: Property or method "user_list" is not defined on the instance but referenced during render. Make sure to declare reactive data properties in the data option. (found in root instance)

Well, we can't help you. Why? Because you didn't post the relevent code. Post the code and someone will help. Also, the Vue message is pretty exact...You need to do what it says....inside the Vue instance, declare your data properties in the data option.

You really can't get a much more descriptive error message.