Allow for separate headers upon conditional

html/includes/forms/schedule-maintenance.inc.php

@@ -11,9 +11,9 @@
  * option) any later version.  Please see LICENSE.txt at the top level of
  * the source code distribution for details.
  */
-header('Content-type: application/json');
 
 if (is_admin() === false) {
+	header('Content-type: text/plain');
     die('ERROR: You need to be admin');
 }
 
@@ -129,5 +129,5 @@ else if ($sub_type == 'del-maintenance') {
         'message' => $message,
     );
 }//end if
-
+header('Content-type: application/json');
 echo _json_encode($response);