Improve error when using wrong YaccOriginalActionKind

[ratmice]

If one uses the wrong action kind e.g. %grmtools{yacckind: Original(UserAction)} instead of %grmtools{yacckind: Original(NoAction)}, the error message could be improved.
Currently this just panics at an unwrap when it tries to get the action type.

thread 'main' (4061320) panicked at ./lrpar/src/lib/ctbuilder.rs:1448:85:
  called `Option::unwrap()` on a `None` value
  note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

Normally I would just file a PR for this, but I'm running out of time today & didn't want to forget.