Enhanced support for value types

[molinch]

It would be nice if there was a dedicated overload for value types, like:

	public static T MissingValue<T>(Nullable<T> input, [CallerArgumentExpression("input")] string? parameterName = null)
		where T: struct
	{
		if (!input.HasValue) throw new ArgumentNullException(parameterName);
		return input.Value;
	}

This way we guarantee that return type has a value.
What do you think? If you agree, I will submit a PR (with the proper format of course and usual behavior).

[ardalis]

Sure, I'm open to it. I'm not sure why you'd accept a Nullable if it has to have a value, though. Why not just say you need a T, not a Nullable ?

[molinch]

The point is to check that a Nullable has a value and from caller be able to use the value without warnings.

If you just use T you cannot check that. While existing Guards prevent "null" on value types they cannot help Roslyn to figure out that the value cannot be "null" anymore.

I put the null under quotes since in reality there's really no null with Nullable but it acts as a null.

[amal-stack]

See #261.