Vale action fails with no useful error

[nickvigilante]

For PRs that have existed within our repo prior to when I introduced vale-action into our workflows, we get a nondescript error:

https://github.com/cockroachdb/docs/runs/6294905552?check_suite_focus=true

Our vale.yml file: https://github.com/cockroachdb/docs/blob/master/.github/workflows/vale.yml

Our .vale.ini file: https://github.com/cockroachdb/docs/blob/master/.vale.ini

[nickvigilante]

This issue seems to occur for branches that have commits prior to when I introduced vale-action into our workflows.

Here's an example PR with the problem: cockroachdb/docs#13799

We can work around this issue by squashing, but it would be nice for some information to be displayed or the exception it's reaching to be fixed.