Fix a crash caused by spell with CAST_FLAG_RUNE_LIST casted by a creature mover. Thanks to Vasago.

src/server/game/Spells/Spell.cpp

@@ -3834,7 +3834,10 @@ void Spell::SendSpellGo()
 
     if (castFlags & CAST_FLAG_RUNE_LIST)                   // rune cooldowns list
     {
-        Player* player = m_caster->ToPlayer();
+        //TODO: There is a crash caused by a spell with CAST_FLAG_RUNE_LIST casted by a creature
+        //The creature is the mover of a player, so HandleCastSpellOpcode uses it as the caster
+        if (Player* player = m_caster->ToPlayer())
+        {
             uint8 runeMaskInitial = m_runesState;
             uint8 runeMaskAfterCast = player->GetRunesState();
             data << uint8(runeMaskInitial);                     // runes state before
@@ -3850,6 +3853,7 @@ void Spell::SendSpellGo()
                 }
             }
         }
+    }
 
     if (castFlags & CAST_FLAG_UNKNOWN_18)                   // unknown wotlk
     {