Hmm where did you find that URL? Is it on your website? Is this coded directly to the website, or being called by the main Launch file?
It sounds like maybe something being pulled in by the main Launch resource.. maybe something that is no longer needed?
I wonder what would happen if you just rebuild the project? Would that file no longer be referenced? Or maybe it's part of an extension... check that all your extensions are up to data, rebuild and test the dev build and see if there is still an issue.