Editor loading indefinitely, JS error "missing )"

Hey there,

on just one(!) of my projects using WP 5.0.2-DE, Enfold 4.5.2 on the same managed hosting the page editor does not load (circle circles forever).
Console gives this error: “Uncaught SyntaxError: missing ) after argument list” for https://ustermed-hno.ch/wp-admin/post.php?post=23&action=edit&lang=de&classic-editor=1:238

There it says:
( 'fetch' in window ) || document.write( '<script src="https://ustermed-hno.ch/wp-includes/js/dist/vendor/wp-polyfill-fetch.min.js?ver=3.0.0' defer='defer"></scr' + 'ipt>' );( document.contains ) || document.write( '<script src="https://ustermed-hno.ch/wp-includes/js/dist/vendor/wp-polyfill-node-contains.min.js?ver=3.26.0-0' defer='defer"></scr' + 'ipt>' );( window.FormData && window.FormData.prototype.keys ) || document.write( '<script src="https://ustermed-hno.ch/wp-includes/js/dist/vendor/wp-polyfill-formdata.min.js?ver=3.0.12' defer='defer"></scr' + 'ipt>' );( Element.prototype.matches && Element.prototype.closest ) || document.write( '<script src="https://ustermed-hno.ch/wp-includes/js/dist/vendor/wp-polyfill-element-closest.min.js?ver=2.0.2' defer='defer"></scr' + 'ipt>' );

It seems to me that the last quotation mark after the last defer should not be a double one, but then again I am not much of a coder.
When switching to standard theme the editor works, but this is uselesse of course.

Any ideas?
Thanks!

• This topic was modified 5 years, 8 months ago by eee_lala.