Codemirror loading fails in certain circumstances due to `innerCodeElem` reference

[ssddanbrown]

Error thrown when viewing page:

Uncaught (in promise) TypeError: innerCodeElem is null
    highlightElem index.mjs:58
    highlight index.mjs:93
    setup page-display.js:38
    promise callback*setup page-display.js:38
    initComponent components.js:95
    init components.js:122
    <anonymous> app.js:37

Can reproduce with the following in the MD editor: (ignoring backslashes)

\```
   blank format
\```

Reported by Reddit user BaccanoMob here.

[guillerg86]

Seems also failed the "copy" shortcut on code block at top right corner

[ssddanbrown]

Closed within 58f6219, to be part of the next patch release.