Showing error on use of invalid arguments

todo/todo

@@ -214,9 +214,10 @@ elif [[ $# == "1" ]];then
     exit 0
   elif [[ $flag == "clear" || $1 == "clear" ]];then clearAllTasks || exit 1
   elif [[ $flag == "get" || $1 == "list" || $1 == "get" ]];then getTasks || exit 1
+else { echo "Error: the argument $1 is not valid"; exit 1;}
   fi
 else
   if [[ $flag == "add" || $1 == "add" ]];then addTask "${*:2}" && getTasks|| exit 1
   elif [[ $flag == "remove" || $1 == "remove" ]];then removeTask $2 || exit 1
-  else usage;fi
+  else { usage; exit 1;};fi
 fi