Warn if invoking with eventargs

[JohanLarsson]

public class ViewModel : INotifyPropertyChanged
{
	private int bar;

	public event PropertyChangedEventHandler PropertyChanged;

	public int Bar
	{
		get { return this.bar; }
		set
		{
			if (value == this.bar)
			{
				this.bar = value;
				↓this.OnPropertyChanged(new PropertyChangedEventArgs(nameof(Bar)));
			}
		}
	}

	protected virtual void OnPropertyChanged(PropertyChangedEventArgs e)
	{
		this.PropertyChanged?.Invoke(this, e);
	}
}

Clumsy and inefficient.