Comparison of incorrectly annotated classes hides original problems

Discovered when playing with F# comparison rules.

Look:

This is the correct error. But once I add a comparison test, the error changes and becomes confusing:

**Expected behavior**

Both errors show up.

**Actual behavior**

The new error hides the original one.

**Known workarounds**

Don't do this.

**Related information**

This is pretty much an edge case and this bug is worth giving it attention only if hides some more serious issue.

Shot in the dark, @auduchinok do you think this can be related to parser rules and/or easily fixed there?