In case anybody else stumbles in here with that same problem (error message after renaming the 'editors' folder), below is a bandaid.

Open /admin/includes/init_includes/init_errors.php and search for: ERROR_EDITORS_FOLDER_NOT_FOUND

On line 179, I found:
// Editor alerts
if (HTML_EDITOR_PREFERENCE != 'NONE' && !is_dir(DIR_FS_CATALOG . 'editors')) {
$messageStack->add(ERROR_EDITORS_FOLDER_NOT_FOUND, 'caution');
}

Replaced that with:
// Editor alerts
if (HTML_EDITOR_PREFERENCE != 'NONE' && !is_dir(DIR_FS_CATALOG . DIR_WS_EDITORS)) {
$messageStack->add(ERROR_EDITORS_FOLDER_NOT_FOUND, 'caution');

Worked like a charm.