Fix "missing return statement" phpstan errors

plugins/enigma/lib/enigma_driver_gnupg.php

@@ -111,6 +111,8 @@ public function init()
         }
 
         $this->db_sync();
+
+        return null;
     }
 
     /**

plugins/enigma/lib/enigma_driver_phpssl.php

@@ -135,16 +135,10 @@ public function delete_key($keyid) {}
      *
      * @return string Hash algorithm name e.g. sha1
      */
-    public function signature_algorithm() {}
-
-    /**
-     * Converts Crypt_GPG_Key object into Enigma's key object
-     *
-     * @param Crypt_GPG_Key $key Key object
-     *
-     * @return enigma_key Key object
-     */
-    private function parse_key($key) {}
+    public function signature_algorithm()
+    {
+        return ''; // TODO
+    }
 
     private function get_openssl_error()
     {

plugins/enigma/lib/enigma_engine.php

@@ -127,7 +127,7 @@ public function load_smime_driver()
      * @param Mail_mime &$message Original message
      * @param int       $mode     Encryption mode
      *
-     * @return enigma_error On error returns error object
+     * @return ?enigma_error On error returns error object
      */
     public function sign_message(&$message, $mode = null)
     {
@@ -214,6 +214,8 @@ public function sign_message(&$message, $mode = null)
             $mime->addPGPSignature($body, $this->pgp_driver->signature_algorithm());
             $message = $mime;
         }
+
+        return null;
     }
 
     /**
@@ -223,7 +225,7 @@ public function sign_message(&$message, $mode = null)
      * @param int       $mode     Encryption mode
      * @param bool      $is_draft Is draft-save action - use only sender's key for encryption
      *
-     * @return enigma_error On error returns error object
+     * @return ?enigma_error On error returns error object
      */
     public function encrypt_message(&$message, $mode = null, $is_draft = false)
     {
@@ -322,6 +324,8 @@ public function encrypt_message(&$message, $mode = null, $is_draft = false)
             $mime->setPGPEncryptedBody($body);
             $message = $mime;
         }
+
+        return null;
     }
 
     /**

plugins/enigma/lib/enigma_key.php

@@ -125,6 +125,8 @@ public function find_subkey($email, $mode)
                 }
             }
         }
+
+        return null;
     }
 
     /**

plugins/enigma/lib/enigma_subkey.php

@@ -51,7 +51,7 @@ public function get_fingerprint()
     /**
      * Returns human-readable name of the key's algorithm
      *
-     * @return string Algorithm name
+     * @return ?string Algorithm name
      */
     public function get_algorithm()
     {
@@ -75,6 +75,8 @@ public function get_algorithm()
             case 22:
                 return 'EdDSA';
         }
+
+        return null;
     }
 
     /**

plugins/example_addressbook/example_addressbook_backend.php

@@ -67,6 +67,8 @@ public function get_group($group_id)
                 return $group;
             }
         }
+
+        return null;
     }
 
     public function get_name()

plugins/managesieve/lib/Roundcube/rcube_sieve_script.php

@@ -178,7 +178,7 @@ public function unset_var($name)
      *
      * @param string $name Variable name
      *
-     * @return string Variable value
+     * @return ?string Variable value
      */
     public function get_var($name)
     {
@@ -188,6 +188,8 @@ public function get_var($name)
                 return $this->vars[$i]['name'];
             }
         }
+
+        return null;
     }
 
     /**

program/actions/contacts/qrcode.php

@@ -129,5 +129,7 @@ public static function check_support()
                 return 'image/png';
             }
         }
+
+        return null;
     }
 }

program/actions/mail/attachment_upload.php

@@ -243,7 +243,7 @@ public static function attachment_success($attachment, $uploadid)
      * @param int    $filesize File size
      * @param string $filetype File mimetype
      *
-     * @return string Error message if the limit is exceeded
+     * @return ?string Error message if the limit is exceeded
      */
     public static function check_message_size($filesize, $filetype)
     {
@@ -252,7 +252,7 @@ public static function check_message_size($filesize, $filetype)
         $size   = 10 * 1024; // size of message body
 
         if (!$limit) {
-            return;
+            return null;
         }
 
         // add size of already attached files
@@ -270,5 +270,7 @@ public static function check_message_size($filesize, $filetype)
             $limit = self::show_bytes($limit);
             return $rcmail->gettext(['name' => 'msgsizeerror', 'vars' => ['size' => $limit]]);
         }
+
+        return null;
     }
 }

program/actions/mail/index.php

@@ -1128,7 +1128,7 @@ public static function part_image_type($part)
         $webp_support = $webp_support || rcube_image::is_convertable('image/webp');
 
         if ((!$tiff_support && $mimetype == 'image/tiff') || (!$webp_support && $mimetype == 'image/webp')) {
-            return;
+            return null;
         }
 
         // Content-Type: image/*...
@@ -1165,6 +1165,8 @@ public static function part_image_type($part)
         ) {
             return $types[$extension];
         }
+
+        return null;
     }
 
     /**

program/include/rcmail.php

@@ -411,6 +411,8 @@ public function get_address_book_id($object)
                 return $index;
             }
         }
+
+        return null;
     }
 
     /**
@@ -863,6 +865,8 @@ public function login_error()
         if ($this->storage && $this->storage->get_error_code() < -1) {
             return self::ERROR_STORAGE;
         }
+
+        return null;
     }
 
     /**
@@ -935,6 +939,8 @@ public function session_error()
 
             return $error;
         }
+
+        return null;
     }
 
     /**
@@ -1539,7 +1545,7 @@ public function log_login($user = null, $failed_login = false, $error_code = 0)
     public function find_asset($path, $minified = true)
     {
         if (empty($path)) {
-            return;
+            return null;
         }
 
         $assets_dir = $this->config->get('assets_dir');
@@ -1558,6 +1564,8 @@ public function find_asset($path, $minified = true)
                 return $path;
             }
         }
+
+        return null;
     }
 
     /**

program/include/rcmail_oauth.php

@@ -1206,6 +1206,8 @@ public function logout_after(array $options)
             // propagate logout request to the identity provider
             $this->rcmail->output->redirect($this->logout_redirect_url); // exit
         }
+
+        return $options;
     }
 
     /**

program/include/rcmail_sendmail.php

@@ -593,6 +593,8 @@ public function header_received()
 
             return wordwrap($http_header, 69, $nldlm);
         }
+
+        return null;
     }
 
     /**
@@ -829,6 +831,8 @@ public function generic_message_footer($isHtml)
                 return $footer;
             }
         }
+
+        return null;
     }
 
     /**

program/lib/Roundcube/rcube_addressbook.php

@@ -434,6 +434,7 @@ public function update($id, $save_cols)
     public function delete($ids, $force = true)
     {
         // empty for read-only address books
+        return false;
     }
 
     /**
@@ -444,6 +445,7 @@ public function delete($ids, $force = true)
     public function undelete($ids)
     {
         // empty for read-only address books
+        return [];
     }
 
     /**
@@ -454,6 +456,7 @@ public function undelete($ids)
     public function delete_all($with_groups = false)
     {
         // empty for read-only address books
+        return false;
     }
 
     /**
@@ -471,6 +474,7 @@ public function delete_all($with_groups = false)
     public function set_group($group_id)
     {
         // empty for address books don't supporting groups
+        return null;
     }
 
     /**

program/lib/Roundcube/rcube_cache.php

@@ -504,6 +504,7 @@ protected function get_item($key)
     protected function add_item($key, $data)
     {
         // to be overwritten by engine class
+        return false;
     }
 
     /**
@@ -516,6 +517,7 @@ protected function add_item($key, $data)
     protected function delete_item($key)
     {
         // to be overwritten by engine class
+        return false;
     }
 
     /**

program/lib/Roundcube/rcube_charset.php

@@ -409,6 +409,8 @@ public static function check($str, $charsets = [])
                 return $charset;
             }
         }
+
+        return null;
     }
 
     /**

program/lib/Roundcube/rcube_csv2vcard.php

@@ -412,7 +412,7 @@ public function __construct($lang = 'en_US')
      * @param bool   $dry_run   Generate automatic field mapping
      * @param bool   $skip_head Skip header line
      *
-     * @return array Field mapping info (dry run only)
+     * @return array|null Field mapping info (dry run only)
      */
     public function import($csv, $dry_run = false, $skip_head = true)
     {
@@ -421,6 +421,7 @@ public function import($csv, $dry_run = false, $skip_head = true)
         if ($charset = rcube_charset::check($csv)) {
             $csv = rcube_charset::convert($csv, $charset);
         }
+
         $csv = preg_replace(['/^[\xFE\xFF]{2}/', '/^\xEF\xBB\xBF/', '/^\x00+/'], '', $csv); // also remove BOM
 
         // Split CSV file into lines
@@ -449,6 +450,8 @@ public function import($csv, $dry_run = false, $skip_head = true)
                 $this->csv_to_vcard($elements);
             }
         }
+
+        return null;
     }
 
     /**

program/lib/Roundcube/rcube_html2text.php

@@ -765,6 +765,8 @@ public function tags_preg_callback($matches)
 
                 return $this->_handle_link($url, $matches[4]);
         }
+
+        return '';
     }
 
     /**

program/lib/Roundcube/rcube_image.php

@@ -87,6 +87,8 @@ public function props()
                 'channels' => $channels,
             ];
         }
+
+        return null;
     }
 
     /**