STS Controller reported light jet traffic on a visual approach flew dangerously low before executing a go-around.

Narrative

Aircraft X was in the left downwind for RWY14; with Aircraft Y in the opposite downwind; and Aircraft Z on an unusual visual approach path at night. I cleared Aircraft Z to land; and they appeared to be aligning for the incorrect runway at very low level not observed on the radar; and I keyed up to confirm they were aligned for runway 14. I instructed Aircraft X to make a right 360 as I observed Aircraft Z go around at very low level and in what I viewed as a risky manner. Aircraft A was holding short of RWY14 waiting for IFR release. Due to the unusual actions by Aircraft Z; I asked Aircraft X if they could start turning direct to RWY14 numbers; to follow Aircraft Y short final to sanitize the airspace and give Aircraft Z more room to maneuver. Aircraft X answered in the affirmative; and I instructed them to make a short approach and RWY14 clear to land number 2 behind Aircraft Y. I called ZOA to coordinate Aircraft Z on the missed and stay with us in the visual pattern; and that I had the next IFR inbound Aircraft B in sight and I could provide visual separation. Aircraft X landed; and I issued exiting instructions and taxi to park instructions monitoring ground. Aircraft A on LC frequency reported a possible overflight by Aircraft Y and asked if that is standard here; I responded negative and advised them that I would give them a number to call. I was working all frequencies combined to a single position at the time; as well as handling all coordination with ZOA.Recommendation: The most unsafe thing that I observed was Aircraft Z on the visual approach at night with minimal approach lighting to RWY14; only REILS. I would have better approach lighting to provide pilots with better navigational awareness in low light conditions as this is not unheard of to encounter at STS; and sanitizing the airspace to deal with an unfamiliar pilot would still be the actions I took. I don't know that I have anything specific to recommend preventing a possible overflight outside of explicitly stating to not overfly taxiway A1.