type alias is not inferred in async functions

[fogfish]

TypeScript Version: 3.5.3

Search Terms: promise, async function, return type in ES5/ES3

Code

type Response = {statusCode: number, body: string}
type IO = Promise<Response>

export async function main(): IO {
  return Promise.resolve({statusCode: 200, body: "ok"})
}

Expected behavior:
Successful compilation

Actual behavior:

error TS1055: Type 'IO' is not a valid async function return type in ES5/ES3 because it does not refer to a Promise-compatible constructor value.

4 export async function main(): IO {

// tsconfig.json
{
  "compilerOptions": {
    "target":"ES2018",
    "module": "commonjs",
    "lib": ["es2016", "es2017.object", "es2017.string", "dom"],
    "strict": true,
    "noImplicitAny": true,
    "strictNullChecks": true,
    "noImplicitThis": true,
    "alwaysStrict": true,
    "noUnusedLocals": true,
    "noUnusedParameters": true,
    "noImplicitReturns": true,
    "noFallthroughCasesInSwitch": false,
    "inlineSourceMap": true,
    "inlineSources": true,
    "experimentalDecorators": true,
    "strictPropertyInitialization":false
  }
}

Playground Link:
Unable to reproduce in playground

Related Issues:
No

[MartinJohns]

Duplicate of #32574.

[typescript-bot]

This issue has been marked as a 'Duplicate' and has seen no recent activity. It has been automatically closed for house-keeping purposes.