NERtcLiveStreamErrorCode constructor Null safety

1. netease_roomkit
2. netease_roomkit
3. NERtcLiveStreamErrorCode
4. NERtcLiveStreamErrorCode constructor

NERtcLiveStreamErrorCode class

1. Constructors
2. NERtcLiveStreamErrorCode
3. Properties
4. hashCode
5. runtimeType
6. Methods
7. noSuchMethod
8. toString
9. Operators
10. operator ==
11. Constants
12. duplicateId
13. internalServerErr
14. invaild
15. invalidLayout
16. notFound
17. numLimit
18. ok
19. requestError
20. requestIsInvaild
21. roomExited
22. userPictureError