[x] Appropriate branch selected => This is a PR against the MTC branch.
[x] Any modified or new methods or classes have helpful JavaDoc and code is thoroughly commented
[na] The description lists all applicable issues this PR seeks to resolve
[na] The description lists any configuration setting(s) that differ from the default settings
[x] All tests and CI builds passing
Description
This PR improves error messages for common cases when the Normalize Field Transform fails:
A corrupt ZIP file is submitted for transformation.
A non-GTFS but valid ZIP file is submitted for transformation.
A GTFS ZIP file is submitted for transformation but the expected table file or field is missing.
The field name parameter for the transformation is not set (i.e. a case where someone started adding a Normalize Field transformation but did not finish configuring it and proceeded to import a GTFS feed).
Checklist
Description
This PR improves error messages for common cases when the Normalize Field Transform fails: