fix(Core/Unit): Invalidate update object cache when changing health in the same world update tick. (#19287)

* fix(Core/Unit): Invalidate update object cache when changing health in the same world update tick.

Should fix an issue when the client sees dead NPCs when they are not.

* Fix styling

* Another codestyle fix

src/server/game/Entities/Unit/Unit.cpp

@@ -21628,6 +21628,20 @@ bool Unit::IsInDisallowedMountForm() const
     return false;
 }
 
+void Unit::SetUInt32Value(uint16 index, uint32 value)
+{
+    Object::SetUInt32Value(index, value);
+
+    switch (index)
+    {
+        // Invalidating the cache on health change should fix an issue where the client sees dead NPCs when they are not.
+        // We might also need to invalidate the cache for some other fields as well.
+        case UNIT_FIELD_HEALTH:
+            InvalidateValuesUpdateCache();
+            break;
+    }
+}
+
 std::string Unit::GetDebugInfo() const
 {
     std::stringstream sstr;

src/server/game/Entities/Unit/Unit.h

@@ -1571,6 +1571,8 @@ public:
     void ApplyAttackTimePercentMod(WeaponAttackType att, float val, bool apply);
     void ApplyCastTimePercentMod(float val, bool apply);
 
+    void SetUInt32Value(uint16 index, uint32 value);
+
     UnitFlags GetUnitFlags() const { return UnitFlags(GetUInt32Value(UNIT_FIELD_FLAGS)); }
     bool HasUnitFlag(UnitFlags flags) const { return HasFlag(UNIT_FIELD_FLAGS, flags); }
     void SetUnitFlag(UnitFlags flags) { SetFlag(UNIT_FIELD_FLAGS, flags); }