Address resolver error messages

Author: epage

text/3493-precise-pre-release-cargo-update.md

@@ -142,6 +142,7 @@ However, we leave the exact API details to the maintainer of the `semver` packag
   A change that makes use of a pre-release version may not be noticed during code review as reviewers don't always check for changes in the lock file.
 - Library crates that require a pre-release version are not well supported since their lock files are ignored by their users (see [future-possibilities])
 - This is an invasive change to cargo with a significant risk for bugs.  This also extends out to packages in the ecosystem that deal with depednency versions.
+- There is a risk that error messages from the resolver may be negatively affected and we might be limited in fixes due to the resolver's current design.
 
 # Rationale and alternatives
 [rationale-and-alternatives]: #rationale-and-alternatives