Undefined array key

[GuySartorelli]

We're trying to read something from an array when the key isn't always there.

https://github.com/silverstripe/cow/actions/runs/8994273555/job/24709468419?pr=254

PHP Warning:  Undefined array key "type" in /home/runner/work/_actions/silverstripe/gha-generate-matrix/v1/job_creator.php on line 156

This works fine - it's just a warning, and it'll result in a falsy value when it's not set which is correct, but we should still fix this to remove the warning.

PRs

• FIX Avoid undefined array key warning gha-generate-matrix#90