Nullability of reference types in type of parameter 'parameter' of 'object? IsWatchedEpisodeProgressVisibleConverter.Convert(object? value, Type targetType, object parameter, CultureInfo culture)' doesn't match implicitly implemented member 'object? IValueConverter.Convert(object? value, Type targetType, object? parameter, CultureInfo culture)' (possibly because of nullability attributes).

Nullability of reference types in type of parameter 'parameter' of 'object IsWatchedEpisodeProgressVisibleConverter.ConvertBack(object? value, Type targetType, object parameter, CultureInfo culture)' doesn't match implicitly implemented member 'object? IValueConverter.ConvertBack(object? value, Type targetType, object? parameter, CultureInfo culture)' (possibly because of nullability attributes).

Nullability of reference types in type of parameter 'parameter' of 'object? RatingConverter.Convert(object? value, Type targetType, object parameter, CultureInfo culture)' doesn't match implicitly implemented member 'object? IValueConverter.Convert(object? value, Type targetType, object? parameter, CultureInfo culture)' (possibly because of nullability attributes).

Nullability of reference types in type of parameter 'parameter' of 'object RatingConverter.ConvertBack(object? value, Type targetType, object parameter, CultureInfo culture)' doesn't match implicitly implemented member 'object? IValueConverter.ConvertBack(object? value, Type targetType, object? parameter, CultureInfo culture)' (possibly because of nullability attributes).

Nullability of reference types in type of parameter 'parameter' of 'object? WatchedEpisodeProgressConverter.Convert(object? value, Type targetType, object parameter, CultureInfo culture)' doesn't match implicitly implemented member 'object? IValueConverter.Convert(object? value, Type targetType, object? parameter, CultureInfo culture)' (possibly because of nullability attributes).

Nullability of reference types in type of parameter 'parameter' of 'object WatchedEpisodeProgressConverter.ConvertBack(object? value, Type targetType, object parameter, CultureInfo culture)' doesn't match implicitly implemented member 'object? IValueConverter.ConvertBack(object? value, Type targetType, object? parameter, CultureInfo culture)' (possibly because of nullability attributes).

Nullability of type of parameter 'e1' doesn't match overridden member (possibly because of nullability attributes).

The variable 'ex' is declared but never used

Dereference of a possibly null reference.