Throw on nil

[Lantua]

This is most recent, I believe:

Combining ? with throwing when there's no reasonable default

If we want to say, "use this or if it's nil, that default", we can write: let a = maybeA ?? A() However, saying "use this or if it's nil, throw" is more verbose (if descriptive): guard let a = maybeA else { throw SomeError() } One might imagine writing let a = maybeA ?? throw SomeError() but this doesn't work: throw X is a statement, not an expression, so it doesn't parse. As @Nevin notes, we can make the right-hand side an explicit closure evaluation: let a = try maybeA() ?? { throw Som…