Fix failure in end-of-run summary for the error stream.

We were getting an "undefined method `path'" error.

While I'm at it, I prevented the RAISE_ERROR_CONFIG_NOTICE
from being printed when that config option is being used.

Fixes #1170.
Merge pull request #1172 from rspec/fix-1170-for-2.99

Fix failure in end-of-run summary for the error stream (for 2.99)