Throwing callins do not decrement their callin depth

This came up in testing, not production.

The base gadgets.lua does not correct the callin depth following errors in nested callins.

`UpdateCallIns` is not self-correcting and reordering subscribers in the list is blocked by `callinDepth == 0`, which seems correct. I'm not sure how to read the `*Raw` calls but they also finish with `UpdateCallins`.

Start in base gadgets.lua and trace UpdateCallIns, including the *Raw call paths, focusing on nested callins that throw. Confirm that callin depth is restored after errors and that subscriber reordering is no longer blocked by a stale depth value; add or run the relevant testing setup mentioned in the issue to verify the behavior.

Written by the indexing model from the issue text.