Core/Creatures: Stop falling if corpse is removed (can happen when alive unit is despawned instantly in air) (#18995)

Do not allow to start waypoint movement when unit is dead

src/server/game/Entities/Creature/Creature.cpp

@@ -295,6 +295,10 @@ void Creature::RemoveCorpse(bool setSpawnTime)
     if (setSpawnTime)
         m_respawnTime = time(NULL) + respawnDelay;
 
+    // if corpse was removed during falling, the falling will continue and override relocation to respawn position
+    if (IsFalling())
+        StopMoving();
+
     float x, y, z, o;
     GetRespawnPosition(x, y, z, &o);
     SetHomePosition(x, y, z, o);

src/server/game/Movement/MovementGenerators/WaypointMovementGenerator.cpp

@@ -98,6 +98,10 @@ bool WaypointMovementGenerator<Creature>::StartMove(Creature* creature)
     if (!i_path || i_path->empty())
         return false;
 
+    // Dont allow dead creatures to move
+    if (!creature->IsAlive())
+        return false;
+
     if (Stopped())
         return true;