fix(Core/Command): crash on set model to npc if not valid (#4874)

src/server/scripts/Commands/cs_npc.cpp

@@ -21,6 +21,7 @@ EndScriptData */
 #include "ScriptMgr.h"
 #include "TargetedMovementGenerator.h"                      // for HandleNpcUnFollowCommand
 #include "Transport.h"
+#include <string>
 
 struct NpcFlagText
 {
@@ -922,6 +923,13 @@ public:
             return false;
         }
 
+        if (!sCreatureDisplayInfoStore.LookupEntry(displayId))
+        {
+            handler->PSendSysMessage(LANG_COMMAND_FACTION_INVPARAM, std::to_string(displayId).c_str());
+            handler->SetSentErrorMessage(true);
+            return false;
+        }
+
         creature->SetDisplayId(displayId);
         creature->SetNativeDisplayId(displayId);