babel/packages/babel-plugin-transform-async-to-generator/test/fixtures/regression/4943/exec.js

"use strict";

function mandatory(paramName) {
  throw new Error(`Missing parameter: ${paramName}`);
}

async function foo({ a, b = mandatory("b") } = {}) {
  return Promise.resolve(b);
}

return foo().then(() => {
  throw new Error('should not occcur');
}, () => true);