Async output in repl is showing after the prompt

[vsemozhetbyt]

• Version: 14.15.0, 15.0.1
• Platform: Windows 10 x64
• Subsystem: repl

> throw new Error();
Uncaught Error
> // prompt is shown

> new Promise((rs, rj) => { rj(); })
Promise { <rejected> undefined }
> (node:4108) UnhandledPromiseRejectionWarning: undefined
(node:4108) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 7)
// no NEW prompt 

> new Promise((rs, rj) => { rj(); }).catch(console.log)
Promise { <pending> }
> undefined
// no NEW prompt 

> new Promise((rs, rj) => { rj(); }).catch(()=>{})
Promise { <pending> }
> // prompt is shown

> new Promise((rs, rj) => { rs(42); }).then(console.log)
Promise { <pending> }
> 42
// no NEW prompt here

[antsmartian]

Ok i'm testing the scenario from master now. The scenario mentioned:

> new Promise((rs, rj) => { rj(); })
Promise { <rejected> undefined }
> (node:4108) UnhandledPromiseRejectionWarning: undefined
(node:4108) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 7)
// no NEW prompt 

is now crashing the repl altogether.

[vsemozhetbyt]

When I try it in 15.11.0 or in today's nightly or canary, I get the same output, now it seems OK:

> new Promise((rs, rj) => { rj(); })
Promise { <rejected> undefined }
> Uncaught undefined
> // Prompt is here!

[antsmartian]

@vsemozhetbyt Yes the other issues still seems to be present.

[BridgeAR]

The reason the Uncaught part now works is that it does not cause a deprecation warning anymore due to the specified unhandled rejection warning.

It is tricky to fix this, since we write on the stream directly. We do not use the regular input methods for e.g., warnings. And what should happen for async writes on the stream? Should they be marked specially? It is currently intermixed with the line input and visualized as input. That's incorrect but difficult to fix, especially in a way that is easy to understand for users.