Fix PHP warnings on dummy QUOTA responses in Courier-IMAP 4.17.1 (#6374)

CHANGELOG

@@ -90,6 +90,7 @@ CHANGELOG Roundcube Webmail
 - Fix touch event issue on messages list in IE/Edge (#5781)
 - Fix so links over images are not removed in plain text signatures converted from HTML (#4473)
 - Fix various issues when downloading files with names containing non-ascii chars, use RFC 2231 (#5772)
+- Fix PHP warnings on dummy QUOTA responses in Courier-IMAP 4.17.1 (#6374)
 
 RELEASE 1.3.7
 -------------

program/lib/Roundcube/rcube_imap_generic.php

@@ -3131,6 +3131,11 @@ class rcube_imap_generic
                     list(, , $quota_root) = $this->tokenizeResponse($line, 3);
 
                     $quotas = $this->tokenizeResponse($line, 1);
+
+                    if (empty($quotas)) {
+                        continue;
+                    }
+
                     foreach (array_chunk($quotas, 3) as $quota) {
                         list($type, $used, $total) = $quota;
                         $type = strtolower($type);