plots: more helpful error message on corrupted/invalid `dvc.yaml`

[dberenbaum]

When dvc.yaml is either corrupted or fails validation, dvc plots show/diff output shows DVC failed to load some plots for following revisions: workspace. There are a couple issues with this:

• It makes it seem like the issue is with one or more of the plots, when it's really about the structure of dvc.yaml and may be completely unrelated to plots.
• It makes it seem like some plots from that revision might still be shown, which isn't true.
• It doesn't give any indication of how to fix it. Other commands like dvc repro give output about what failed like:

'./dvc.yaml' is invalid.

While scanning a simple key, in line 24, column 1
  24 dfdf

Could not find expected ':', in line 25, column 1
  25

For dvc plots show, can we show something similar?

For dvc plots diff, this might not make sense by default since there could be many revisions. However, it still seems like we could improve the message. For example, it could say something like Failed to read dvc.yaml for the following revisions (add -v to see errors): workspace.

[dberenbaum]

On second thought, should dvc plots show ever include DVC failed to load some plots for the following revisions? It is always operating in the current workspace, so mentioning revisions at all seems confusing.

[francisquintallauzon]

+1 on this issue. I am having the same issue with hint on resolution. We are considering using DVC as part of our MLOps tool stack, but this kind of issue (no/unclear error messages) is really a break on adoption for us.

[serious-gist]

Is their any progress on this issue, we are currently facing this issue out of nowhere

[dberenbaum]

@serious-gist If you post the full output of what you are getting, we may be able to help resolve it.