lastName property Null safety

1. baguette
2. Account
3. Account
4. lastName property

Account class

1. Constructors
2. Account
3. fromJson
4. Properties
5. address
6. contact
7. data
8. email
9. firstName
10. hashCode
11. image
12. lastName
13. runtimeType
14. userID
15. Methods
16. noSuchMethod
17. toJson
18. toString
19. Operators
20. operator ==