fix error not being handled if name is null

Barotrauma/BarotraumaShared/SharedSource/LuaCs/LuaCsHook.cs

@@ -98,13 +98,13 @@ namespace Barotrauma
 
 		public void Add(string name, string hookName, LuaCsFunc hook, ACsMod owner = null)
 		{
-			name = name.ToLower();
-
 			if (name == null || hookName == null || hook == null)
 			{
 				throw new ScriptRuntimeException("Hook.Add: name, hookName and hook must not be null.");
 			}
 
+			name = name.ToLower();
+
 			if (!hookFunctions.ContainsKey(name))
 			{
 				hookFunctions.Add(name, new Dictionary<string, (LuaCsHookCallback, ACsMod)>());