reject toPrompt promise on exit (eg with ESC key)

this is an open issue in the library: terkelg#362

here's a fix for this that someone made a while ago (which has not been merged for some reason): terkelg#369

This PR makes the same fix in our internal fork

lib/prompts.js

@@ -11,7 +11,7 @@ function toPrompt(type, args, opts={}) {
     const onExit = opts.onExit || noop;
     p.on('state', args.onState || noop);
     p.on('submit', x => res(onSubmit(x)));
-    p.on('exit', x => res(onExit(x)));
+    p.on('exit', x => rej(onExit(x)));
     p.on('abort', x => rej(onAbort(x)));
   });
 }