Core: Combat/threat system rewrite (PR #19930)

- PvE combat is now always mutual. UNIT_FLAG_IN_COMBAT is backed by actual references to the units we're in combat with.
- PvP combat is now also tracked, and almost always mutual; spells like Vanish and Feign Death can break this rule. That means we can easily determine a list of players we're fighting.
- By extension, IsInCombatWith now has sensible behavior when invoked on nonplayers.
- Threat and combat systems are no longer the same.
  - They still have an enforced relationship (threat implies combat - clearing combat clears threat)...
  - ...but we can have combat without threat. A creature (with threat list) isn't considered to be engaged until it has an entry on its threat list...
  - ...which means we can now faithfully replicate retail engage behavior. Combat on projectile launch - engagement start on projectile impact. Yay for progress!
- AI method refactor, as already ported in 6113b9d - `JustEngagedWith`, `JustEnteredCombat` and `JustExitedCombat`.
- Vehicle threat is now properly pooled on the main vehicle body (fixes #16542).
- Various edge case bug fixes for threat redirects (Misdirection "cancelling" Vigilance and similar).
- Target re-selection is now significantly faster.
- Fixed a ton of other smaller edge case bugs, probably.

Closes #7951 and #19998.

1 files changed, 4 insertions, 1 deletions

diff --git a/src/server/scripts/Pet/pet_hunter.cpp b/src/server/scripts/Pet/pet_hunter.cpp
index 5a295c04f05..50c61f4c885 100644
--- a/src/server/scripts/Pet/pet_hunter.cpp
+++ b/src/server/scripts/Pet/pet_hunter.cpp
@@ -238,8 +238,11 @@ class spell_pet_guard_dog : public SpellScriptLoader
                 Unit* caster = eventInfo.GetActor();
                 caster->CastSpell(nullptr, SPELL_PET_GUARD_DOG_HAPPINESS, aurEff);
 
+                Unit* target = eventInfo.GetProcTarget();
+                if (!target->CanHaveThreatList())
+                    return;
                 float addThreat = CalculatePct(ASSERT_NOTNULL(eventInfo.GetSpellInfo())->Effects[EFFECT_0].CalcValue(caster), aurEff->GetAmount());
-                eventInfo.GetProcTarget()->GetThreatManager().AddThreat(caster, addThreat, GetSpellInfo(), false, true);
+                target->GetThreatManager().AddThreat(caster, addThreat, GetSpellInfo(), false, true);
             }
 
             void Register() override