TYPO3 Core

Reported by Johannes Schlier:

Example configuration:

editor:
  config:
    removePlugins:
      - image
      - specialchar

"image" is migrated which leaves "specialchar", but the array is encoded to JSON as

{"1":"specialchar"}

["specialchar"]

Resulting in a CKEditor5 runtime error because the array method some() is tried to be executed on an object:

VM2902 ckeditor5-core.js:17 Uncaught (in promise) TypeError: e.some is not a function
    at v (VM2902 ckeditor5-core.js:17:2271)
    at VM2902 ckeditor5-core.js:17:1146
    at Array.filter (<anonymous>)
    at x.init (VM2902 ckeditor5-core.js:17:1134)
    at w.initPlugins (VM2902 ckeditor5-core.js:37:2082)
    at VM2846 ckeditor5-editor-classic.js:14:636
    at new Promise (<anonymous>)
    at w.create (VM2846 ckeditor5-editor-classic.js:14:593)
    at CKEditor5Element.firstUpdated (VM2808 ckeditor5.js:13:3194)