Welp, first up, fatal errors:
111230 [Thread-4] ERROR com.fs.starfarer.combat.CombatMain - java.lang.NullPointerException
java.lang.NullPointerException
at com.fs.starfarer.combat.ai.ProximityFuseAI.updateDamage(Unknown Source)
at com.fs.starfarer.combat.ai.ProximityFuseAI.<init>(Unknown Source)
at com.fs.starfarer.loading.specs.ifsuper.super(Unknown Source)
at com.fs.starfarer.loading.specs.ifsuper.super(Unknown Source)
at com.fs.starfarer.combat.entities.ship.A.J.o00000(Unknown Source)
at com.fs.starfarer.combat.entities.ship.A.J.fireProjectile(Unknown Source)
at com.fs.starfarer.combat.entities.ship.trackers.OoOO.Óo0000(Unknown Source)
at com.fs.starfarer.combat.entities.ship.trackers.OoOO.o00000(Unknown Source)
at com.fs.starfarer.combat.entities.ship.trackers.D.o00000(Unknown Source)
at com.fs.starfarer.combat.entities.ship.trackers.D.o00000(Unknown Source)
at com.fs.starfarer.combat.entities.ship.trackers.OoOO.Ô00000(Unknown Source)
at com.fs.starfarer.combat.entities.ship.A.J.advance(Unknown Source)
at com.fs.starfarer.combat.systems.oOoO.advanceLinked(Unknown Source)
at com.fs.starfarer.combat.systems.oOoO.advance(Unknown Source)
at com.fs.starfarer.combat.entities.Ship.fire(Unknown Source)
at com.fs.starfarer.combat.entities.Ship.advance(Unknown Source)
at com.fs.starfarer.combat.CombatEngine.advanceInner(Unknown Source)
at com.fs.starfarer.combat.CombatEngine.advance(Unknown Source)
at com.fs.starfarer.combat.CombatState.traverse(Unknown Source)
at com.fs.state.AppDriver.begin(Unknown Source)
at com.fs.starfarer.combat.CombatMain.main(Unknown Source)
at com.fs.starfarer.StarfarerLauncher.super(Unknown Source)
at com.fs.starfarer.StarfarerLauncher$1.run(Unknown Source)
at java.lang.Thread.run(Thread.java:745)
To replicate, put a Net Launcher or Heavy Net Launcher on a ship, load up the simulator, and fire it.
Edit: Or, presumably, an Ultraheavy Net of Enrapture, though I didn't test that one this time.
For me (running on macos), this crash replicates 100% of the time.
At least one other person (running on windows) has reported that it doesn't happen at all for them.
As far as I can tell, the mod doesn't have file-case-sensitivity issues; all the files are in lower case, and all the references to files that I've found are also in lower case.
Since the crash is happening entirely in vanilla code, I figure it's reasonable to toss up a thread here and ask if anyone has any idea what's going wrong.