Reworking error message for unresolved evar subterm of another evar.

This is a reworking of 7fd28dc9: instead of using words such as
"domain of", "codomain of" to refer to a position in the instance of
the original evar, we simply display the instance and the name of the
unresolved evar in this instance. This is both simpler and more
informative. (The positional words remain useful for printing the
evar_map in debugging though.)

In passing, this fixes #8369 (Not_found in printing message about an
unresolved subevar).

Incidentally add possible breaking while printing "in environment".

0 files changed, 0 insertions, 0 deletions