Prevent operations on destroyed views

[ocavue]

I encountered the following error during my unit tests:

Uncaught TypeError: Cannot read properties of null (reading 'matchesNode')
    at EditorView.updateStateInner (chunk-VVQZWLTC.js?v=83ef0d59:4795:45)
    at EditorView.updateState (chunk-VVQZWLTC.js?v=83ef0d59:4770:10)
    at EditorView.dispatch (chunk-VVQZWLTC.js?v=83ef0d59:5115:10)
    at y-prosemirror.js?v=ab00c66d:1219:12
    at Map.forEach (<anonymous>)
    at updateMetas (y-prosemirror.js?v=ab00c66d:1212:7)

This error appears in view.dispatch(tr) at lib.js#L33, which is wrapped in a eventloop.timeout / setTimeout.

While I haven't specifically tried to reproduce this error during typical user operations, it may not pose a problem for actual users since it seems to be a timing issue, and automated tests generally run faster than human interactions. Nevertheless, I believe it's a good idea to check view.isDestroyed in asynchronous (i.e., setTimeout) operations to prevent such issues.

In this PR, I added a view.isDestroyed check before view.dispatch(tr) in this place.

Sidenote: In sync-plugin.js, there are also some this.prosemirrorView.dispatch() calls. It could be a good idea to check view.isDestroyed before calling .dispatch(), but I'm not certain if it's necessary. @dmonad Do you think I should add view.isDestroyed check for them too?