communicator: add errhandler_type back and debugger GAP issue

[jsquyres]

This is an issue corresponding to PR #11818. Filing this as an issue just so that we can track it on the project board.

It affects main and v5.0.x.

[wzamazon]

#11818 was merged.

I opened a PR to backport to v5.0.x branch: #11821

[wzamazon]

backport merged.