Possible Admin Scheduler bug

**User environment -**
OS: MacOS 15.6.1
Browser: Safari 18.6
Browser: Firefox 143.0.1

**Server environment -**
OS: RHEL 8.10
Web server: Apache 2.4.37
PHP: php-fpm 7.3.20
Mod Security: 2.9.6 (Disabled for testing) / Ruleset 4.18.0
Cloudflare

While tracking down "Fetch Errors" and "Invalid Taken" errors I believe I've discovered a bug in the Admin > Tools > Scheduler.

For completeness the Invalid Token errors were caused by Safari > Settings > Privacy > Prevent cross-site tracking. This issue does not appear in Firefox. Unfortunately disabling this feature in Safari disables it for all websites!

I have managed to eliminate all Fetch Errors with the exception of the Admin > Tools > Scheduler which seems to be caused by a MIME type mismatch for "clipboard-helper.js". The MIME type reported is (text/html) and I think it should be (application/javascript), but I'm not a software developer and not sure about this. The result of the type mismatch prevents execution of the javascript.

This issue appears in both Safari and Firefox.

The 404 errors for Grav-Editor-Pro are expected since I have not purchased that plugin.

Start in Admin > Tools > Scheduler and inspect the network request for clipboard-helper.js, including the response MIME type and the asset path. Trace where that asset is served and verify the scheduler loads and executes it with an application/javascript response rather than text/html.

Written by the indexing model from the issue text.