editor property "postfix" does not seem to do anything

[hasezoey]

Currently for question type editor the property postfix does nothing (not even the default .txt is applied), this is probably a error in external-editor, but i also open it here because it also affects this library.

repro code:

import * as inquirer from "inquirer";
await inquirer.prompt([{ type: "editor", default: "testmsg", name: "someprop", postfix: ".md" }])
// the resulting file does not have any extension
// resulting file path is something like "/tmp/tmp-144678H0IG3Le6CyFH"

NodeJS 18.6.0 inquirer 9.0.1 Linux Manjaro 21.3.4