This is an easy one:
matches = @/([ (.) whispers, "(.)" to you. ]/.Match("HALLO WURLD!!!")
causes BooBinding to freak; the error message (expression:1:2: unexpected char '[') seems to indicate that BooBinding is trying to parse the contents within the builtin regex expression @/ (stuff) / instead of skipping to the very end.
The error occurs whenever code completion would normally be invoked, AKA the '.' and the '('.