ConnectionRequiredError constructor Null safety

1. sendbird_sdk
2. error
3. ConnectionRequiredError
4. ConnectionRequiredError constructor

ConnectionRequiredError class

1. Constructors
2. ConnectionRequiredError
3. Properties
4. code
5. hashCode
6. message
7. runtimeType
8. stackTrace
9. Methods
10. byaction
11. noSuchMethod
12. toJson
13. toString
14. Operators
15. operator ==