fix(developer): crash in context help

Fixes sillsdev/keyman-issues#6207.
Fixes sillsdev/keyman-issues#5801.
Fixes sillsdev/keyman-issues#5742.
Fixes sillsdev/keyman-issues#6186.
Fixes sillsdev/keyman-issues#6124.
Fixes sillsdev/keyman-issues#5647.
Fixes sillsdev/keyman-issues#5726.
Fixes sillsdev/keyman-issues#6149.
Fixes sillsdev/keyman-issues#6228.
Fixes sillsdev/keyman-issues#6001.
Fixes sillsdev/keyman-issues#6148.
Fixes sillsdev/keyman-issues#6159.
Fixes sillsdev/keyman-issues#6171.

This fixes a crash when context help is unable to determine the
current context.