I think the errors are normal in this case, if you have enabled lightmapping in your scene then you need to make sure that any model affected by those lights includes UV1 coordinates.
I think the default primitives don’t do that, so try uploading a model of your own with UV1 coords. Or use the auto-unwrap option on the inspector when selecting a model asset (check article at the bottom):
OK, in my actual project where I noticed this error, ie not this minimal project, I use the basic box/plane primitives all over the place, and lightmapping. Do you think this error will actually cause any runtime issues? The web page on iOS would occasionally pop up a message like “the page has repeated errors” and these were the only errors that the console showed.