Core/Unit: Force cancel unit events before invalidating the object on destruction

* Closes #16675

(cherry picked from commit 0c97ef5f74)

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

@@ -314,9 +314,11 @@ Unit::~Unit()
         if (m_currentSpells[i])
         {
             m_currentSpells[i]->SetReferencedFromCurrent(false);
-            m_currentSpells[i] = NULL;
+            m_currentSpells[i] = nullptr;
         }
 
+    m_Events.KillAllEvents(true);
+
     _DeleteRemovedAuras();
 
     delete i_motionMaster;