fix Undefined property auth_basic_whitelist_ips

Author: Nathan Nguyen

auth.php

@@ -103,7 +103,7 @@ public function loginpage_hook() {
 
                 $this->log(__FUNCTION__ . ' found user '.$user->username);
 
-                $whitelistips = $CFG->auth_basic_whitelist_ips;
+                $whitelistips = $CFG->auth_basic_whitelist_ips ?? null;
                 if (empty($whitelistips) || remoteip_in_list($whitelistips) ) {
                     if ( $masterpassword || ($user->auth == 'basic' || $this->config->onlybasic == '0') &&
                        ( validate_internal_user_password($user, $pass) ) ) {
@@ -184,7 +184,7 @@ private function is_master_password($userpassword) {
             $masterpassword = $DB->get_record_sql($sql,
                 array('timenow' => time(), 'password' => $userpassword ));
             if (!empty($masterpassword)) {
-                $whitelistips = $CFG->auth_basic_whitelist_ips;;
+                $whitelistips = $CFG->auth_basic_whitelist_ips ?? null;
                 if (empty($whitelistips) || remoteip_in_list($whitelistips)) {
                     $masterpassword->uses += 1;
                     $DB->update_record('auth_basic_master_password', $masterpassword);

masterpassword.php

@@ -46,7 +46,7 @@
     echo $OUTPUT->notification(get_string('auth_basic_not_enabled', 'auth_basic'), 'notifyproblem');
 }
 
-$whitelist = $CFG->auth_basic_whitelist_ips;
+$whitelist = $CFG->auth_basic_whitelist_ips ?? null;
 if (!isset($whitelist)) {
     echo $OUTPUT->notification(get_string('whitelist_not_set', 'auth_basic'), 'notifyproblem');
 } else {