The issue with debug mode was actually not cleaning up after `try_enter`:
location `&tstate` was pointing to got invalidated and received some “garbage”
(actually, values that got stored on the stack afterwards). But pointer to that
garbage was still stored in `msg_list`, so next attempt to check it resulted in
a crash.
Problem: when processing cycle such as
:for pat in [' \ze*', ' \zs*']
: try
: let l = matchlist('x x', pat)
: $put ='E888 NOT detected for ' . pat
: catch
: $put ='E888 detected for ' . pat
: endtry
:endfor
`:let l = …` throwing an error causes this error to be caught after
color_cmdline attempts to get callback for highlighting next line (the one with
`$put = 'E888 NOT…`). Saving/restoring state prevents this from happening.
This also attempted to fix problem with cancelling input() on error by avoiding
standard error printing facilities (assumed thrown error message is the
problem), but with no luck so far.
