rustc: Stop calling error! in resolve

These are taken care of with compiler errors later on, no need to spam with
extra unformatted information unconditionally.

Closes #14225
auto merge of #14239 : alexcrichton/rust/issue-14225, r=huonw

These are taken care of with compiler errors later on, no need to spam with
extra unformatted information unconditionally.

Closes #14225