Scripts/Commands: Fix crash caused by .set npc model

Port From (https://github.com/TrinityCore/TrinityCore/commit/ff2cd4a0322fc2942323702a37844b0cfa963ce4)

Source/Framework/Constants/Language.cs

@@ -375,7 +375,7 @@ namespace Framework.Constants
         CommandModifyArena = 306,
         CommandFactionNotfound = 307,
         CommandFactionUnknown = 308,
-        CommandFactionInvparam = 309,
+        CommandInvalidParam = 309,
         CommandFactionDelta = 310,
         FactionList = 311,
         FactionVisible = 312,

Source/Game/Chat/Commands/ModifyCommands.cs

@@ -425,7 +425,7 @@ namespace Game.Chat
 
                     if (i == ReputationMgr.ReputationRankThresholds.Length - 1)
                     {
-                        handler.SendSysMessage(CypherStrings.CommandFactionInvparam, rankTxt);
+                        handler.SendSysMessage(CypherStrings.CommandInvalidParam, rankTxt);
                         return false;
                     }
 

Source/Game/Chat/Commands/NPCCommands.cs

@@ -1219,6 +1219,12 @@ namespace Game.Chat
                     return false;
                 }
 
+                if (!CliDB.CreatureDisplayInfoStorage.ContainsKey(displayId))
+                {
+                    handler.SendSysMessage(CypherStrings.CommandInvalidParam, args);
+                    return false;
+                }
+
                 creature.SetDisplayId(displayId);
                 creature.SetNativeDisplayId(displayId);