Yup, same thing, and after it started appearing it wouldn’t go away, I used a day old github image where the classic ckeditor was working and now it doesn’t work. The only way to get strapi working was to remove the plugins folder, dependencies and go back to the default (non ck) editor.
It says styled comp, but I am suspicious that this is not the real issue, in my package json I am importing: "styled-components": "^5.2.0".
By clicking around after the error appears and refreshing the pages I got this:
“Cannot GET /admin/plugins/content-manager/collectionType/application::category.category”
sharing in case it helps.
I don’t know if it is related but the Media Library also errors out for me (500), does it work for you?
At risk of jinxing it… I added brackets as suggested in the Strap Slack and now all works, at least so far. I tried with Classic editor and then with the one I created and published to npm and works fine too.
@Nils check if your imports are like this in the CKEditor/index.js
import { CKEditor } from ‘@ckeditor/ckeditor5-react’;
import ClassicEditor from ‘@ckeditor/ckeditor5-build-classic’;