If `prepare-inception` is given an unknown resource file reference, the error message is not helpful

Current situation

If a prepare-inception function references an unknown resource, the error message in the workflow execution log is:

[2023-09-12T18:15:42] [job c0fe3ba6-3182-44d6-8ea2-4cc7fb5bca38] Running function actionsprepare-inceptionv1
[2023-09-12T18:15:42] [job c0fe3ba6-3182-44d6-8ea2-4cc7fb5bca38] ERROR: Unexpected execution error: string indices must be integers.

It gives a hint of the error location (in prepare-inception), but that's it.

Desired outcome

A more helpful error message:

[2023-09-12T18:20:40] [job f2690fd3-f84d-4380-b825-19d7f50af59b] ERROR: Unknown file resources: report.html.