CI: codecov steps fail for frontend workflow (JS)

[flodolo]

Workflow: https://github.com/mozilla/pontoon/blob/main/.github/workflows/frontend.yml

Example: https://github.com/mozilla/pontoon/actions/runs/10954546833

warning - 2024-09-20 06:47:04,989 -- xcrun is not installed or can't be found.
warning - 2024-09-20 06:47:05,351 -- No gcov data found.
warning - 2024-09-20 06:47:05,351 -- coverage.py is not installed or can't be found.
info - 2024-09-20 06:47:05,380 -- Found 0 coverage files to report
Error: No coverage reports found. Please make sure you're generating reports successfully.
Warning: Codecov:
                        Failed to properly upload report: The process '/home/runner/work/_actions/codecov/codecov-action/v4/dist/codecov' failed with exit code 1

What I don't understand is how these JS tests work.

The rest runs npm test --coverage. If I run locally, it creates a coverage folder in tag-admin, which doesn't make any sense.
Even more so considering that the content of this folder is the same if I run npm test within the tag-admin folder (which explains why the Non-frontend JavaScript workflow is the only one where codecov ever succeeded).