Running Project has missing BS4 .map file

I’m not sure when this came up. I have bootstrap as the included theme in the project. (Yes, I have the ability to change themes in the app, but this is before I do any changes, eg, so bootstrap is the only theme used when the error occurs).

DevTools failed to parse SourceMap:

This file does not appear in the above folder. I don’t see anything wrong with the rendering or functionality of the BS4 controls, etc.

It’s a variation on this - nothing to worry about.

Only with debugger on - that explains the randomness.