Correctly use groups parameter only when its not empty

Fix #9745

settings/ajax/createuser.php

@@ -5,18 +5,20 @@ OC_JSON::checkSubAdminUser();
 
 if(OC_User::isAdminUser(OC_User::getUser())) {
 	$groups = array();
-	if( isset( $_POST["groups"] )) {
+	if (!empty($_POST["groups"])) {
 		$groups = $_POST["groups"];
 	}
 }else{
 	if (isset($_POST["groups"])) {
 		$groups = array();
+		if (!empty($_POST["groups"])) {
 			foreach ($_POST["groups"] as $group) {
 				if (OC_SubAdmin::isGroupAccessible(OC_User::getUser(), $group)) {
 					$groups[] = $group;
 				}
 			}
-		if(count($groups) === 0) {
+		}
+		if (empty($groups)) {
 			$groups = OC_SubAdmin::getSubAdminsGroups(OC_User::getUser());
 		}
 	} else {