Core/AI: Fix assertion triggered with PetAI derived scripts (#21254)

* Core/AI: Fix assertion triggered with PetAI derived scripts

Fix an assertion triggered when spawning through ".npc add" or from SQL db table a Creature with AI set to a custom AI inheriting from PetAI.

src/server/game/AI/AIException.cpp

@@ -0,0 +1,23 @@
+/*
+ * Copyright (C) 2008-2018 TrinityCore <https://www.trinitycore.org/>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "AIException.h"
+
+InvalidAIException::InvalidAIException(char const* _message)
+{
+    message().assign(_message);
+}

src/server/game/AI/AIException.h

@@ -0,0 +1,40 @@
+/*
+ * Copyright (C) 2008-2018 TrinityCore <https://www.trinitycore.org/>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef TRINITY_AIEXCEPTION_H
+#define TRINITY_AIEXCEPTION_H
+
+#include "Define.h"
+#include <exception>
+#include <string>
+
+class TC_GAME_API InvalidAIException : public std::exception
+{
+public:
+    InvalidAIException(char const* _message);
+    ~InvalidAIException() throw() { }
+
+    char const* what() const noexcept override { return msg_.c_str(); }
+
+protected:
+    std::string & message() throw() { return msg_; }
+
+private:
+    std::string msg_;
+};
+
+#endif

src/server/game/AI/CoreAI/PetAI.cpp

@@ -17,17 +17,20 @@
  */
 
 #include "PetAI.h"
+#include "AIException.h"
+#include "Creature.h"
 #include "Errors.h"
+#include "Group.h"
+#include "Log.h"
+#include "MotionMaster.h"
+#include "ObjectAccessor.h"
 #include "Pet.h"
 #include "Player.h"
 #include "Spell.h"
-#include "ObjectAccessor.h"
 #include "SpellHistory.h"
-#include "SpellMgr.h"
-#include "Creature.h"
-#include "Util.h"
-#include "Group.h"
 #include "SpellInfo.h"
+#include "SpellMgr.h"
+#include "Util.h"
 
 int32 PetAI::Permissible(Creature const* creature)
 {
@@ -43,6 +46,8 @@ int32 PetAI::Permissible(Creature const* creature)
 
 PetAI::PetAI(Creature* c) : CreatureAI(c), i_tracker(TIME_INTERVAL_LOOK)
 {
+    if (!me->GetCharmInfo())
+        throw InvalidAIException("Creature doesn't have a valid charm info");
     UpdateAllies();
 }
 
@@ -152,7 +157,7 @@ void PetAI::UpdateAI(uint32 diff)
             if (!spellInfo)
                 continue;
 
-            if (me->GetCharmInfo() && me->GetSpellHistory()->HasGlobalCooldown(spellInfo))
+            if (me->GetSpellHistory()->HasGlobalCooldown(spellInfo))
                 continue;
 
             // check spell cooldown

src/server/game/AI/CreatureAISelector.cpp

@@ -16,6 +16,7 @@
  * with this program. If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include "AIException.h"
 #include "Creature.h"
 #include "CreatureAISelector.h"
 #include "CreatureAIFactory.h"
@@ -84,8 +85,16 @@ namespace FactorySelector
             return ASSERT_NOTNULL(sCreatureAIRegistry->GetRegistryItem("PetAI"))->Create(creature);
 
         // scriptname in db
-        if (CreatureAI* scriptedAI = sScriptMgr->GetCreatureAI(creature))
-            return scriptedAI;
+        try
+        {
+            if (CreatureAI* scriptedAI = sScriptMgr->GetCreatureAI(creature))
+                return scriptedAI;
+        }
+        catch (InvalidAIException const& e)
+        {
+            TC_LOG_ERROR("entities.unit", "Exception trying to assign script '%s' to Creature (Entry: %u), this Creature will have a default AI. Exception message: %s",
+                creature->GetScriptName().c_str(), creature->GetEntry(), e.what());
+        }
 
         return SelectFactory<CreatureAI>(creature)->Create(creature);
     }