MacOS 10.13.6
Chrome Version 85.0.4183.102 (Official Build) (64-bit)
I'm editing https://en.wikipedia.org/w/index.php?title=User:RoySmith/drafts/Robert_Weinberg_(urban_planner)&oldid=978201279. I've just added a reference, and when I go to save it, it hangs in the edit box. Hitting either the Apply Change or the X button have no effect, but I'm able to dismiss the edit box by typing ESC.
In the javascript console. I've got:
Uncaught TypeError: Cannot read property 'isReadOnly' of null at VeDmMWTransclusionInlineNode.ve.dm.Node.getOffset (load.php?lang=en&modules=ext.visualEditor.core&skin=vector&version=64but:55) at VeDmMWTransclusionInlineNode.ve.Node.getOuterRange (load.php?lang=en&modules=ext.visualEditor.core&skin=vector&version=64but:6) at VeDmMWTransclusionModel.ve.dm.MWTransclusionModel.updateTransclusionNode (<anonymous>:511:402) at <anonymous>:367:175 at fire (load.php?lang=en&modules=jquery%2Coojs-ui-core|jquery.ui&skin=vector&version=1rnvg:46) at Object.add [as done] (load.php?lang=en&modules=jquery%2Coojs-ui-core|jquery.ui&skin=vector&version=1rnvg:46) at <anonymous>:366:411 at <anonymous>:16:96 at OO.ui.Process.execute (<anonymous>:16:754) at VeUiMWCitationDialog.OO.ui.Dialog.executeAction (<anonymous>:40:46)
Screenshot attached.