Molly could have died a warlock in PG.
Actually, this one is interesting. Molly getting in trouble in Proven Guilty is an indirect result of Harry picking up Lasciel's Coin. Harry had consciously avoided Michael ever since, to the point where he hadn't seen him in a couple of years (especially odd because they're pretty much best bros). Because Harry wasn't around, he didn't pick up any of the signs from Molly, and she didn't have the opportunity to casually talk to him about it. Mab even lampshades it in Cold Days (page 480 on Nook):
"...Then when she went to explore the Art, you elected not to interfere until such time as she found herself in dire straits..."
Harry's absence, especially after his frequent presence and mysterious example, is one of the things that engineered Molly's circumstances. So, in Mirror, Mirror, if he didn't pick up the Coin, maybe Molly never went warlock in the first place. I'd actually like that, because the Mirrorverse might be a bit boring if everything is objectively worse in every regard, you know?