Consider this program:

import 'dart:isolate';
import 'dart:html' show HttpRequest;

useHttpRequest() {
  print('In isolate.');
  HttpRequest.getString('test.dart').then((text) => print(text));
}

main() {
  print('Starting isolate');
  spawnFunction(useHttpRequest);
}

All that shows up in the console is:

"Starting isolate undefined:1"

I had expected to see:

"Starting isolate test.dart:10
[From isolate] In isolate. test.dart:5
[From isolate] DOM access is not enabled in this isolate

­0 HttpRequest._create (file:///Volumes/data/b/build/slave/dartium-mac-inc/build/src/out/Release/gen/webkit/bindings/dart/dart/html/HttpRequest.dart:60:3)

­1 HttpRequest.HttpRequest (file:///Volumes/data/b/build/slave/dartium-mac-inc/build/src/out/Release/gen/webkit/bindings/dart/dart/html/HttpRequest.dart:58:35)

­2 HttpRequest.request (file:///Volumes/data/b/build/slave/dartium-mac-inc/build/src/out/Release/gen/webkit/bindings/dart/dart/html/HttpRequest.dart:10:15)

­3 HttpRequest.getString (file:///Volumes/data/b/build/slave/dartium-mac-inc/build/src/out/Release/gen/webkit/bindings/dart/dart/html/HttpRequest.dart:5:19)

­4 useHttpRequest (http://127.0.0.1:56653/web_editor/test.dart:6:26)

This is almost what happens if I modify useHttpRequest:

useHttpRequest() {
  print('In isolate.');
  try {
    HttpRequest.getString('test.dart').then((text) => print(text));
  } catch (e, trace) {
    print('$e\n$trace');
  }
}

So the following questions arise:

1. Why isn't the the text "In isolate" printed in the console?
2. Why isn't the uncaught exception diagnosed?
3. Why doesn't the debugger pause on the exception?
4. Why does the console say "undefined:1"?

I'll file a separate bug about HttpRequest not being available.