`ProcessFilesGlob` calls the callback concurrently, so this test needs to lock the `processedFiles` map to prevent panics. See [here](https://app.circleci.com/pipelines/github/ethereum-optimism/optimism/73932/workflows/951eb7de-0611-4bea-b4de-5d3a56c9bf37/jobs/3021176) for an example of this happening.