Minor documentation change as well as parameter check.

RecrownedGTK.Tools/CommandProcessor/CommandEngine.cs

@@ -82,9 +82,10 @@ namespace RecrownedGTK.Tools.CommandProcessor
         /// Check if the command exists using it's invokes string.
         /// </summary>
         /// <param name="command">A string that will invoke the command.</param>
-        /// <returns></returns>
+        /// <returns>Returns true if the given invoke string exists as a command and false if command parameter is null.</returns>
         public bool ContainsCommand(string command)
         {
+            if (command == null) return false;
             for (int i = 0; i < commands.Count; i++)
             {
                 if (commands[i].IsInvoked(command)) return true;