TRANSCODE {.'} Causes Assertion Failure

[hostilefork]

This should be an error (you can not do to tuple! [_ '], and shouldn't be able to... trash is legal in sequence slots since TUPLE! and PATH! can't have antiforms or quasiforms, but they can have quoted forms so this is out).

And it is an error... the assertion happens during error delivery. A good general fix seems to require some broader thinking about the invariants of tuple and path scanning.