That is totally what I opened this thread to post. But it's already done for me, so, yeah.
This. Except with these caveats:
She's largely a female Joker, The Dark Knight style. Her lore text even lines right up with that, though the recent Jinx vs. Vi does not; based on the lore text she has the combination of wit and luck the Joker has and would easily outfox blunt force like Vi every time. There is no sign Vi is clever enough to get past Jinx's tricks and lack of ethical or moral constraints. How would Vi EVER get close enough to do anything at all? Probably only by Jinx letting her. And chances are, from what the lore suggests... if Jinx gets caught, it's probably going to be part of the plan.
In fact, probably the only reason Vi and Caitlyn would still be alive is, to borrow the words... they're "too much fun!" They could keep doing this forever...
I will further note that the only way Vi winning can make sense in a "present-day-league-of-legends" context is if Jinx is somehow being made available to summoners from prison... yeah, OK.
All that said, there is still some case for "neutral" instead of "evil". The killing is still likely just a means to an end, not the objective itself. All indications are she has a total lack of morality... and an extremely warped or non-existent concept of other living beings. Mental illness is, after, a certainty - she has a doctor's note. When someone legitimately doesn't understand right from wrong, it's hard to classify them as good OR evil. In terms of morality, they have more in common with an animal than a saint OR an actual, intentional criminal. And that seems to be where she lands in terms of the good vs. evil scale (in potentially considerable contrast to the Joker, depending on which of his lore you're looking at and your perspective.)
She would definitely intentionally shoot people on whim, insofar as aiming and firing with intent to cause a bullet (or more likely, a vast spray of bullets) to hit them. Whether "killing" means the same thing to her as it does to a sane person is an entirely different matter. And that's where all the messy grey area comes in.
I do think it's fairly clear the best way to survive Jinx is to be more fun intact than exploded in a chaotic blaze of glory... the more boring you are, the more likely you are to end up in many pieces. So if you ever meet a crazy gal with blue hair and a rocket launcher... entertain her!