Run-time error '9': Subscript out of range (when using a Class Module)

I'm using a Class Module to run a macro when there is a change, in this instance in Column A.
I get an error message when I use the "Undo" function, for some reason.
The error message is: Run-time error '9': Subscript out of range
The debug points to line: UndoList = Application.CommandBars("Standard").Controls("&Undo").List(1)
Is there any way to stop this?


THIS WORKBOOK

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MODULE

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CLASS MODULE

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Oddly, it seems to work fine for me.

BTW, you can avoid the looping with your worksheet exists function

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Have you tried Undo after one (1) operation. The issue is not there if two or more things are done.
I have Windows 10 and Office 2013.
Also with the above code, does this relate to the error I'm getting.

Bumping up.