Core/Pet: Attempt to fix assertions triggered when summoning pets (#26501)

* Core/Pet: Attempt to fix an assertion triggered when re-summoning the current pet

* Core/Pet: Attempt to fix an assertion triggered when stabling a pet while in a vehicle

* Core/Pet: Attempt to fix an assertion triggered when stabling a pet and casting spell 6962

* Core/Pet: Attempt to fix an assertion triggered when casting spell 6962 while being dead

* Core/Pet: Attempt to fix an assertion triggered when summoning a pet while on vehicle 34775

* Handle cases in a generic way

* Code cleanup

* Core/Pet: Attempt to fix an assertion triggered when summoning a pet while on vehicle 34775 with a new character

(cherry picked from commit e203ecda88a327c4e93588f39cc4ffdcf99b30f7)

3 files changed, 25 insertions, 3 deletions

diff --git a/src/server/game/Entities/Pet/Pet.cpp b/src/server/game/Entities/Pet/Pet.cpp
index 74c86e4c7ca..aba5a14ad77 100644
--- a/src/server/game/Entities/Pet/Pet.cpp
+++ b/src/server/game/Entities/Pet/Pet.cpp
@@ -210,6 +210,10 @@ bool Pet::LoadPetFromDB(Player* owner, uint32 petEntry, uint32 petnumber, bool c
         return false;
     }
 
+    // Don't try to reload the current pet
+    if (petStable->CurrentPet && owner->GetPet() && petStable->CurrentPet.value().PetNumber == petInfo->PetNumber)
+        return false;
+
     SpellInfo const* spellInfo = sSpellMgr->GetSpellInfo(petInfo->CreatedBySpellId, owner->GetMap()->GetDifficultyID());
 
     bool isTemporarySummon = spellInfo && spellInfo->GetDuration() > 0;
@@ -330,9 +334,13 @@ bool Pet::LoadPetFromDB(Player* owner, uint32 petEntry, uint32 petnumber, bool c
     // PET_SAVE_NOT_IN_SLOT(100) = not stable slot (summoning))
     if (slot == PET_SAVE_NOT_IN_SLOT)
     {
+        uint32 petInfoNumber = petInfo->PetNumber;
+        if (petStable->CurrentPet)
+            owner->RemovePet(nullptr, PET_SAVE_NOT_IN_SLOT);
+
         auto unslottedPetItr = std::find_if(petStable->UnslottedPets.begin(), petStable->UnslottedPets.end(), [&](PetStable::PetInfo const& unslottedPet)
         {
-            return unslottedPet.PetNumber == petInfo->PetNumber;
+            return unslottedPet.PetNumber == petInfoNumber;
         });
         ASSERT(!petStable->CurrentPet);
         ASSERT(unslottedPetItr != petStable->UnslottedPets.end());
@@ -343,6 +351,19 @@ bool Pet::LoadPetFromDB(Player* owner, uint32 petEntry, uint32 petnumber, bool c
         // old petInfo pointer is no longer valid, refresh it
         petInfo = &petStable->CurrentPet.value();
     }
+    else if (PET_SAVE_FIRST_STABLE_SLOT <= slot && slot <= PET_SAVE_LAST_STABLE_SLOT)
+    {
+        auto stabledPet = std::find_if(petStable->StabledPets.begin(), petStable->StabledPets.end(), [petnumber](Optional<PetStable::PetInfo> const& pet)
+        {
+            return pet && pet->PetNumber == petnumber;
+        });
+        ASSERT(stabledPet != petStable->StabledPets.end());
+
+        std::swap(*stabledPet, petStable->CurrentPet);
+
+        // old petInfo pointer is no longer valid, refresh it
+        petInfo = &petStable->CurrentPet.value();
+    }
 
     // Send fake summon spell cast - this is needed for correct cooldown application for spells
     // Example: 46584 - without this cooldown (which should be set always when pet is loaded) isn't set clientside
diff --git a/src/server/game/Entities/Player/Player.cpp b/src/server/game/Entities/Player/Player.cpp
index 708f07b34d6..8c4b8db42bf 100644
--- a/src/server/game/Entities/Player/Player.cpp
+++ b/src/server/game/Entities/Player/Player.cpp
@@ -28718,6 +28718,9 @@ Pet* Player::SummonPet(uint32 entry, float x, float y, float z, float ang, PetTy
         return nullptr;
     }
 
+    if (petType == SUMMON_PET && petStable.CurrentPet)
+        RemovePet(nullptr, PET_SAVE_NOT_IN_SLOT);
+
     PhasingHandler::InheritPhaseShift(pet, this);
 
     pet->SetCreatorGUID(GetGUID());
diff --git a/src/server/game/Handlers/NPCHandler.cpp b/src/server/game/Handlers/NPCHandler.cpp
index 9854aaa6710..4d618e612ec 100644
--- a/src/server/game/Handlers/NPCHandler.cpp
+++ b/src/server/game/Handlers/NPCHandler.cpp
@@ -598,8 +598,6 @@ void WorldSession::HandleUnstablePet(WorldPacket& recvData)
     }
     else
     {
-        std::swap(*stabledPet, petStable->CurrentPet);
-
         // update current pet slot in db immediately to maintain slot consistency, dismissed pet was already saved
         CharacterDatabasePreparedStatement* stmt = CharacterDatabase.GetPreparedStatement(CHAR_UPD_CHAR_PET_SLOT_BY_ID);
         stmt->setUInt8(0, PET_SAVE_AS_CURRENT);