Good question. Looks like a logical error on my part, if so, mea culpa. After taking a cursory look through Switch.pm I can't see why "?..?" should cause a different error from "/../", but then again it's not obvious to me why either should cause an error at all, so that's not saying much.

To be honest, if I were having the OP's problem I'd still try replacing all "/../" with "m/../" (well, no, I'd rewrite the code to not use Switch.pm, but anyway) just on the off-chance, so maybe my first node still has some merit.