fix(Core/Combat): drop dangling current victim on phase change crash (azerothcore#26020)

Co-authored-by: blinkysc <blinkysc@users.noreply.github.com>

Author: blinkysc

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

@@ -15321,30 +15321,10 @@ void Unit::SetPhaseMask(uint32 newPhaseMask, bool update)
 
         if (!sScriptMgr->CanSetPhaseMask(this, newPhaseMask, update))
             return;
-
-        // Phase-related threat updates are done AFTER the phase change below
     }
 
     WorldObject::SetPhaseMask(newPhaseMask, false);
 
-    // Now update threat online states with the new phase mask applied
-    if (IsCreature() || (IsPlayer() && !ToPlayer()->IsGameMaster() && !ToPlayer()->GetSession()->PlayerLogout()))
-    {
-        // Update online state for units that have me on their threat list
-        for (auto const& pair : GetThreatMgr().GetThreatenedByMeList())
-        {
-            if (ThreatReference* ref = pair.second)
-                ref->UpdateOffline();
-        }
-
-        // Update online state for units on my threat list
-        if (!IsPlayer())
-        {
-            for (ThreatReference* ref : GetThreatMgr().GetModifiableThreatList())
-                ref->UpdateOffline();
-        }
-    }
-
     if (!IsInWorld())
     {
         return;

src/test/server/game/Combat/ThreatManagerTest.cpp

@@ -734,7 +734,7 @@ TEST_F(ThreatManagerIntegrationTest,
 }
 
 // ============================================================================
-// Phase Change + Threat Offline State Tests (SetPhaseMask order fix)
+// Phase Change + Threat Offline State Tests
 // ============================================================================
 
 TEST_F(ThreatManagerIntegrationTest,
@@ -748,6 +748,10 @@ TEST_F(ThreatManagerIntegrationTest,
     // Move B to a different phase
     _creatureB->SetPhase(2);
 
+    // Online state is refreshed lazily on the next threat update tick (matches
+    // TrinityCore - SetPhaseMask itself does not touch threat)
+    _creatureA->TestGetThreatMgr().Update(ThreatManager::THREAT_UPDATE_INTERVAL);
+
     // B should now be offline on A's threat list (different phases)
     // The list is not empty if we include offline, but empty if we don't
     EXPECT_TRUE(_creatureA->TestGetThreatMgr().IsThreatenedBy(_creatureB, true));  // includeOffline