This gives a nice message about the location of errors in a large
tablegen file, which is much more useful for users
I'm not all that concerned about a test just trying to get my head around this. I just realized this is counting the number of results from the thing that is being cast which makes a lot more sense. I thought it was trying to count the number of results for the ValueType itself and I couldn't figure out how to write that.
case -> cast ?