What is the problem?
When opening the Visual Editor, I am sometimes seeing the error in the browser console:
Uncaught TypeError: observer.unobserve is not a function
at <anonymous>:242:484
at Object.fire (<anonymous>:622:949)
at VeInitMwDesktopArticleTarget.ve.init.mw.DesktopArticleTarget.transformPage (<anonymous>:22:323)
at VeInitMwDesktopArticleTarget.ve.init.mw.DesktopArticleTarget.activate (<anonymous>:8:684)
at <anonymous>:142:236
at mightThrow (load.php?lang=en&modules=ext.CodeMirror.lib|ext.centralNotice.bannerHistoryLogger%2CchoiceData%2Cdisplay%2CimpressionEventsSampleRate%2CkvStore%2CstartUp|jquery%2Coojs-ui-core%2Coojs-ui-widgets|jquery.ui|mediawiki.diff|wikibase.client.linkitem.init&skin=vector&version=wkhrv:351)
at process (load.php?lang=en&modules=ext.CodeMirror.lib|ext.centralNotice.bannerHistoryLogger%2CchoiceData%2Cdisplay%2CimpressionEventsSampleRate%2CkvStore%2CstartUp|jquery%2Coojs-ui-core%2Coojs-ui-widgets|jquery.ui|mediawiki.diff|wikibase.client.linkitem.init&skin=vector&version=wkhrv:352)The error appears to happen here.
It does not always happen. I am not sure the exact steps to reproduce reliably.
Steps to reproduce problem
- Find an article
- Open the browser console
- Open Visual Editor
Environment
Browser: Chromium 87, Firefox 78
Wiki(s): https://en.wikipedia.beta.wmflabs.org