Don't return undefined $_SESSION['secure_token'] (#8705)

Avoid `PHP Warning: Undefined array key "secure_token" in /roundcubemail/program/lib/Roundcube/rcube.php on line 1002` seen with PHP 8 and secure_urls enabled.

1 files changed, 3 insertions, 1 deletions

diff --git a/program/lib/Roundcube/rcube.php b/program/lib/Roundcube/rcube.php
index dfdffc9af..31fba2eeb 100644
--- a/program/lib/Roundcube/rcube.php
+++ b/program/lib/Roundcube/rcube.php
@@ -996,7 +996,9 @@ class rcube
                 $_SESSION['secure_token'] = $plugin['value'];
             }
 
-            return $_SESSION['secure_token'];
+            if (!empty($_SESSION['secure_token'])) {
+                return $_SESSION['secure_token'];
+            }
         }
 
         return false;