consolidate: improve robustness

Currently it's possible to break the consolidation cycle by adding a typo or problem to the Dockerfile of a new version of an accepted extension. That's problematic and relies excessive helicopter parenting of the repo.

The consolidation script should gracefully handle extension fetch failures, either by skipping the malformed data, and/or entirely skipping the version with the malformed Dockerfile. An error message should be printed out/logged whenever a failure/skip occurs.