Ensure we don't throw a fatal error if composer isn't set up correctly

[dkotter]

Description of the Change

We have some code that outputs an error message if composer hasn't been set up correctly but this code has a bug in it that ends up causing a fatal error instead. This PR fixes that issue and also removes the translation of this error message as no real need to translate strings that end up in the error log.

How to test the Change

1. On the develop branch, clone the repo but don't run composer install
2. Activate the plugin and notice a fatal error happens
3. Run composer install and notice the error goes away
4. Checkout this branch and remove the vendor directory
5. Notice the fatal error doesn't happen anymore but an admin error notice shows instead

Changelog Entry

Fixed - Fix a fatal error that occurs if composer install hasn't been run

Credits

Props @dkotter

Checklist:

• I agree to follow this project's Code of Conduct.
• I have updated the documentation accordingly.
• I have added tests to cover my change.
• All new and existing tests pass.

[peterwilsoncc]

LGTM, just a note about it being a warning rather than an error.

Internationalization has been removed, was that intentional or did you just wish to get rid of the escaping?

[dkotter]

Internationalization has been removed, was that intentional or did you just wish to get rid of the escaping?

Yeah, mentioned this in the PR description (though realize that's easy to miss) but my view was this is a message meant to be in the error log so doesn't seem like there's any real need to translate that. It's easy enough to add back though if you feel like it should be there.