A Promise returned from one of the VM's methods fails to settle if the request encounters an error on the page inside the iframe

This directly related to [this issue](https://github.com/stackblitz/core/issues/1955).

To reproduce, checkout [this branch](https://github.com/emilefokkema/stackblitz-sdk/tree/issue/11/reproduction), run `npm run start`, navigate to `/examples/embed-project-vm/` and click on "Embed project".