correctly fails implicit search for invalid implicit macros

There was a rare corner case when implicit search wouldn’t discard
an invalid implicit macro (e.g. the one with mismatching macro impl or
the one with macro impl defined in the same compilation run) during
typechecking the corresponding candidate in typedImplicit1. This is now fixed.
Merge pull request #3137 from xeno-by/topic/implicit-macros-invalidate-on-error

correctly fails implicit search for invalid implicit macros