Correction of possible problems

Signed-off-by: Valentin Popov <info@valentineus.link>

restorebackup.php

@@ -45,7 +45,7 @@ if ($mform->is_cancelled()) {
 }
 
 /* Processing the received file */
-if ($data = $mform->get_data()) {
+if (!empty($data = $mform->get_data())) {
     $content = $mform->get_file_content('backupfile');
     local_webhooks_restore_backup($content);
     redirect($managerservice, new lang_string('restorefinished', 'moodle'));