[CKEditor 5] Upcoming editor v18.0.0 release has breaking changes that will crash MathType

[mlewand]

The upcoming CKEditor 5 release contains a change in style processor that will break the MathType plugin. It causes instant crash with:

mathtype.js:66 TypeError: Cannot read property 'stylesProcessor' of undefined
    at new h (element.js:114)
    at b.domToView (domconverter.js:430)
    at b.domChildrenToView (domconverter.js:466)
    at domChildrenToView.next (<anonymous>)
    at b.domToView (domconverter.js:445)
    at o.toView (htmldataprocessor.js:79)
    at plugin.js:383
    at view (plugin.js:370)
    at xt.e.on.priority (downcasthelpers.js:654)
    at xt.fire (emittermixin.js:209)

The breaking changes are listed in the "StylesProcessor is no longer singleton" pull request.

[mlewand]

We went though your code and compiled a list of changes required to make it work, here it is:

• ps://github.com/wiris/html-integrations/blob/stable/packages/mathtype-ckeditor5/src/plugin.js#L242 – you shouldn’t use the ViewDocFrag constructor (it’s protected), but writer.createDocumentFragment(). You need to change it because we added new param to the constructor (the writer method didn’t change).
• https://github.com/wiris/html-integrations/blob/stable/packages/mathtype-ckeditor5/src/plugin.js#L239 – the constructor now gets the view document (see nightly docs here: https://ckeditor5.github.io/docs/nightly/ckeditor5/latest/api/module_engine_dataprocessor_xmldataprocessor-XmlDataProcessor.html#function-constructor)
• https://github.com/wiris/html-integrations/blob/stable/packages/mathtype-ckeditor5/src/plugin.js#L350 – same here.
• https://github.com/wiris/html-integrations/blob/stable/packages/mathtype-ckeditor5/src/plugin.js#L379 – and here (nightly docs: https://ckeditor5.github.io/docs/nightly/ckeditor5/latest/api/module_engine_dataprocessor_htmldataprocessor-HtmlDataProcessor.html)
• https://github.com/wiris/html-integrations/blob/stable/packages/mathtype-ckeditor5/src/integration.js#L171 – use model.createPositionBefore() https://ckeditor5.github.io/docs/nightly/ckeditor5/latest/api/module_engine_model_model-Model.html#function-createPositionBefore

It's possible that we missed something, but this should do it. We based this on the stable branch.

[xaviripo]

Solved as of MathType for CKEditor 5 version 7.19.0.