Better runtime errors

[alubbe]

If my test throws a runtime error, it gets printed as an AssertionError, which swallows the stack trace. For example,

var Promise = require("bluebird");
test("foo", Promise.coroutine(function*(t){
    throw new Error("asd");
}));

only prints

1. foo
  AssertionError: Promise rejected → Error: asd

It would be really helpful to get a stack trace here.

[jamestalmage]

👍