win(cm).focus() is not a function

[FengmiAlice]

Describe the issue

In my Vue 2.x project, I'm using CodeMirror 5.x version, and occasionally I encounter an error where the code cannot be edited. The error is located in the onMouseDown event within the CodeMirror.js source code, specifically at win(cm).focus(). How can I resolve this?

Browser and platform

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Reproduction link

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