Cannot set mode due to possible incorrect MIME type on request

[johnslipper]

Hi there. I'm getting the following error trying to set the editor mode to JSON using the .setMode("brace/mode/json") function:

refused to execute script from 'https://localhost:8000/mode-json.js' because its MIME type ('text/html') is not executable, and strict MIME type checking is enabled.

Could this be that the service worker request does not have the correct MIME type?

[walstper]

If question is still actual - this can happen if you pass incorrect 'mode' value.
Check it's validity.