The using directive for 'System.Collections.Generic' appeared previously in this namespace

Cannot convert null literal to non-nullable reference type.

'ViewModelBase.PropertyChanged' hides inherited member 'ReactiveObject.PropertyChanged'. Use the new keyword if hiding was intended.

Nullability of reference types in type of 'event PropertyChangedEventHandler ViewModelBase.PropertyChanged' doesn't match implicitly implemented member 'event PropertyChangedEventHandler? INotifyPropertyChanged.PropertyChanged'.

'MTextBoxEditor.PropertyChanged' hides inherited member 'ReactiveObject.PropertyChanged'. Use the new keyword if hiding was intended.

Nullability of reference types in type of 'event PropertyChangedEventHandler MTextBoxEditor.PropertyChanged' doesn't match implicitly implemented member 'event PropertyChangedEventHandler? INotifyPropertyChanged.PropertyChanged'.

'VoicerSelector.PropertyChanged' hides inherited member 'ReactiveObject.PropertyChanged'. Use the new keyword if hiding was intended.

Nullability of reference types in type of 'event PropertyChangedEventHandler VoicerSelector.PropertyChanged' doesn't match implicitly implemented member 'event PropertyChangedEventHandler? INotifyPropertyChanged.PropertyChanged'.

Nullability of reference types in type of parameter 'exception' of 'void MemoryLogger.Log<TState>(LogLevel logLevel, EventId eventId, TState state, Exception exception, Func<TState, Exception, string> formatter)' doesn't match implicitly implemented member 'void ILogger.Log<TState>(LogLevel logLevel, EventId eventId, TState state, Exception? exception, Func<TState, Exception?, string> formatter)' (possibly because of nullability attributes).