[PE-D] Undo undoes beyond done actions

[nus-pe-script]

It seems like I can undo things that I did not even do in the first place. The following are the steps I took:

Start:

Undo, (correctly does not undo as expected):

After undoable command,
add n/Jane Doherty p/1847291074 e/janedoe123@gmail.com a/Coral Street, 5th Avenue, #02-04, pr/500.00 i/none s/pending t/caterer:

Undo, (correctly undoes as expected):

Undo again, (erroneously undoes unexpectedly):

Undo all the way, (still undoes unexpectedly until all are deleted even when I didn't add them):

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Labels: severity.Medium type.FunctionalityBug
original: jayasting98/ped#4