I don't know whether this should be reported:
Added injury to Head but it should be impossible to hit it. pawn=Bear_Grizzly39651 dinfo=(def=Blunt, amount= 19, instigator=Muffalo39655, angle=270.0)
Verse.Log:Error(String, Boolean)
Verse.Hediff_Injury:PostAdd(Nullable`1)
Verse.HediffSet:AddDirect(Hediff, Nullable`1, DamageResult)
Verse.Pawn_HealthTracker:AddHediff(Hediff, BodyPartRecord, Nullable`1, DamageResult)
Verse.DamageWorker_AddInjury:FinalizeAndAddInjury_Patch1(Object, Pawn, Hediff_Injury, DamageInfo, DamageResult)
Verse.DamageWorker_AddInjury:FinalizeAndAddInjury(Pawn, Single, DamageInfo, DamageResult)
Verse.DamageWorker_Blunt:ApplySpecialEffectsToPart(Pawn, Single, DamageInfo, DamageResult)
Verse.DamageWorker_AddInjury:ApplyDamageToPart_Patch1(Object, DamageInfo, Pawn, DamageResult)
Verse.DamageWorker_AddInjury:ApplyToPawn(DamageInfo, Pawn)
Verse.DamageWorker_AddInjury:Apply(DamageInfo, Thing)
Verse.Thing:TakeDamage_Patch1(Object, DamageInfo)
CombatExtended.Verb_MeleeAttackCE:ApplyMeleeDamageToTarget(LocalTargetInfo)
CombatExtended.Verb_MeleeAttackCE:TryCastShot_Patch1(Object)
Verse.Verb:TryCastNextBurstShot()
Verse.Verb:WarmupComplete()
Verse.Verb:TryStartCastOn_Patch1(Object, LocalTargetInfo, Boolean, Boolean)
RimWorld.Pawn_MeleeVerbs:TryMeleeAttack(Thing, Verb, Boolean)
Verse.AI.<MakeNewToils>c__Iterator0:<>m__1()
Verse.AI.<FollowAndMeleeAttack>c__AnonStorey3:<>m__0()
Verse.AI.JobDriver:DriverTick()
Verse.AI.Pawn_JobTracker:JobTrackerTick()
Verse.Pawn:Tick_Patch1(Object)
Verse.TickList:Tick()
Verse.TickManager:DoSingleTick()
Verse.TickManager:TickManagerUpdate()
Verse.Game:UpdatePlay()
Verse.Root_Play:Update()
Looks like Verse.DamageWorker_AddInjury still has some problem. I'm using version b8a233a2590c634f5fe3f058cd745b55ae23e742