Fix unexpected error message when mail refresh involves folder auto-unsubscribe (#6923)

CHANGELOG

@@ -14,6 +14,7 @@ CHANGELOG Roundcube Webmail
 - Fix so messages in threads with no root aren't displayed separately (#4999)
 - Fix regression where "Open in new window" action didn't work (#7155)
 - Fix PHP Warning: array_filter() expects parameter 1 to be array, null given in subscriptions_option plugin (#7165)
+- Fix unexpected error message when mail refresh involves folder auto-unsubscribe (#6923)
 
 RELEASE 1.4.2
 -------------

program/lib/Roundcube/rcube_imap.php

@@ -2946,6 +2946,9 @@ class rcube_imap extends rcube_storage
         // Add/Remove folders according to some configuration options
         $this->list_folders_filter($result, $root . $name, ($list_extended ? 'ext-' : '') . 'subscribed');
 
+        // Save the last command state, so we can ignore errors on any following UNSEBSCRIBE calls
+        $state = $this->save_conn_state();
+
         if ($list_extended) {
             // unsubscribe non-existent folders, remove from the list
             if ($name == '*' && !empty($this->conn->data['LIST'])) {
@@ -2977,6 +2980,8 @@ class rcube_imap extends rcube_storage
             }
         }
 
+        $this->restore_conn_state($state);
+
         return $result;
     }
 
@@ -4573,6 +4578,31 @@ class rcube_imap extends rcube_storage
         return $date->format('d-M-Y H:i:s O');
     }
 
+    /**
+     * Remember state of the IMAP connection (last IMAP command).
+     * Use e.g. if you want to execute more commands and ignore results of these.
+     *
+     * @return array Connection state
+     */
+    protected function save_conn_state()
+    {
+        return array(
+            $this->conn->error,
+            $this->conn->errornum,
+            $this->conn->resultcode,
+        );
+    }
+
+    /**
+     * Restore saved connection state.
+     *
+     * @param array $state Connection result
+     */
+    protected function restore_conn_state($state)
+    {
+        list($this->conn->error, $this->conn->errornum, $this->conn->resultcode) = $state;
+    }
+
     /**
      * This is our own debug handler for the IMAP connection
      */