[trainer] check specifically for file url in failure_message, fixing crash in Xcode 15 when running in Apple Silicon

[TheMetalCode]

Checklist

• I've run bundle exec rspec from the root directory to see all new and existing tests pass
• I've followed the fastlane code style and run bundle exec rubocop -a to ensure the code style is valid
• I see several green ci/circleci builds in the "All checks have passed" section of my PR (connect CircleCI to GitHub if not)
• I've read the Contribution Guidelines
• I've updated the documentation if necessary.
• I've added or updated relevant unit tests.

Motivation and Context

Resolves #21475

Description

It would appear that with Xcode 15 there are at least some cases where test failure data would not include a url property. Adjusting the check in failure_message to specifically verify the presence of self.document_location_in_creating_workspace&.url prior to attempting to append it to the failure message seems liek the most straightforward resolution.

Testing Steps

[rogerluan]

Thanks for this fix, @TheMetalCode ! 🙏

I'd normally try to figure out what is causing this value to be nil, but it might genuinely be just a different behavior of the new Xcode 15, when run specifically on Apple Silicon.

I'm personally facing this issue in CircleCI Xcode 15 Apple Silicon and think this is a valid fix.

I wish we had unit tests to cover this case, could you look into adding tests to cover this scenario @TheMetalCode ? 🙏 Also, looks like CI is failing in this PR

[TheMetalCode]

@rogerluan Will add tests and address CI, hope to get to that this evening.

[jszumski]

@rogerluan @joshdholtz this PR fixes a crash against the GA version of Xcode 15, could you take a look when you have a moment? Thanks!

[rogerluan]

💪 thanks for fixing this

[raid5]

Excellent! When might we expect a new release?

[rogerluan]

Hard to tell for sure, but I think soon enough! Meanwhile you can point your fastlane gem to master to use this 🙏

[geoff-sheldon-bfg]

Does this fix the issue described in #21295 ?

[rogerluan]

I don't think so...? Why do you think they're related @geoff-sheldon-bfg ?