devcontainers/ci build fails, without error message

[This GitHub Action build](https://github.com/enola-dev/enola/actions/runs/8055630768/job/22002913664?pr=560) which is from [this PR](https://github.com/enola-dev/enola/pull/560) where I'm introducing the action from this project fails strangely:

There is no failure error message (that I can tell), but it seems to just stop half way. (Note also how the "yellow dot" is still "spinning", but that `test-devcontainer` job has a red failure.)

I'm only see this in the job that uses this action. Everything works fine for other build jobs with other actions.

I don't suppose you have ANY idea what's going on here? What could be causing this?