I see some issue with daming pawn/enemy,if the hit blow away one body part but not fatal hit leading to death, system dont count that body part to health bar,may be leading to undie pawn.

This is debug blog of this pawn:
Exception ticking Kyle (at (56, 0, 37)): System.NullReferenceException: Object reference not set to an instance of an object
at RimWorld.Pawn_RelationsTracker.Notify_PawnKilled (System.Nullable`1[T] dinfo, Verse.Map mapBeforeDeath) [0x0001d] in <0ee2c524c4be441e9b7f8bfcb20aca6f>:0
at (wrapper dynamic-method) Verse.Pawn.Verse.Pawn.Kill_Patch4(Verse.Pawn,System.Nullable`1<Verse.DamageInfo>,Verse.Hediff)
at (wrapper dynamic-method) Verse.Pawn_HealthTracker.Verse.Pawn_HealthTracker.CheckForStateChange_Patch3(Verse.Pawn_HealthTracker,System.Nullable`1<Verse.DamageInfo>,Verse.Hediff)
at Verse.Pawn_HealthTracker.Notify_HediffChanged (Verse.Hediff hediff) [0x0000b] in <0ee2c524c4be441e9b7f8bfcb20aca6f>:0
at Verse.Hediff.set_Severity (System.Single value) [0x000b4] in <0ee2c524c4be441e9b7f8bfcb20aca6f>:0
at Verse.HealthUtility.AdjustSeverity (Verse.Pawn pawn, Verse.HediffDef hdDef, System.Single sevOffset) [0x00026] in <0ee2c524c4be441e9b7f8bfcb20aca6f>:0
at Verse.HediffGiver_Bleeding.OnIntervalPassed (Verse.Pawn pawn, Verse.Hediff cause) [0x0002b] in <0ee2c524c4be441e9b7f8bfcb20aca6f>:0
at Verse.Pawn_HealthTracker.HealthTick () [0x0047b] in <0ee2c524c4be441e9b7f8bfcb20aca6f>:0
at (wrapper dynamic-method) Verse.Pawn.Verse.Pawn.Tick_Patch1(Verse.Pawn)
at Verse.TickList.Tick () [0x0015c] in <0ee2c524c4be441e9b7f8bfcb20aca6f>:0
Verse.Log:Error(String, Boolean)
Verse.TickList:Tick()
Verse.TickManager:DoSingleTick()
Verse.TickManager:TickManagerUpdate()
Verse.Game:UpdatePlay()
Verse.Root_Play:Update()