Token requests can trigger a "UnhandledPromiseRejectionWarning" in version 4.0.0+

[dnicolson]

Summary

It is possible to trigger an UnhandledPromiseRejectionWarning: AssertionError [ERR_ASSERTION]: Invalid 'grant_type' type warning for invalid requests in version 4.0.0 and later.

Steps to Reproduce

1. Start the following server in 4.0.0 or 4.1.0:

const { OAuth2Server } = require('oauth2-mock-server');

async function startServer() {
    let server = new OAuth2Server();
    await server.issuer.keys.generate('RS256');
    await server.start(8080, 'localhost');
}

startServer();

2. Run curl --request POST --url http://localhost:8080/token --header 'Content-Type: multipart/form-data;'

Expected Behavior

An assertion failure message. The equivalent code in version 3.2.0 works as expected:

const { OAuth2Server } = require('oauth2-mock-server');

async function startServer() {
    let server = new OAuth2Server();
    await server.issuer.keys.generateRSA();
    await server.start(8080, 'localhost');
}

startServer();

Environment

• oauth2-mock-server version: 4.1.0
• Noje.JS version: 14.15.0
• NPM version: 6.14.8
• Operating System: macOS 11.6

[nulltoken]

@dnicolson Great catch!

A fix is on its way in #142

[nulltoken]

@dnicolson Fixed and published in https://www.npmjs.com/package/oauth2-mock-server/v/4.1.1