ThemeProvider constructor Null safety

1. diginote
2. theme_provider
3. ThemeProvider
4. ThemeProvider constructor

ThemeProvider class

1. Constructors
2. ThemeProvider
3. Properties
4. backgroundColour
5. hashCode
6. hasListeners
7. isDarkMode
8. runtimeType
9. themeManager
10. Methods
11. addListener
12. dispose
13. init
14. noSuchMethod
15. notifyListeners
16. removeListener
17. setBackgroundColour
18. toggleIsDarkMode
19. toString
20. Operators
21. operator ==