And add a better error message.
By using `void` instead of `await`, any error thrown is not caught
by surrounding try-catch blocks.
I could continue to use `void` and explicitly handle any thrown errors
by using `.catch`, but most likely the time savings is minimal and
this makes the code more complex.
As suggested in review: The `GITHUB_REPOSITORY` environment variable is
only available on Actions. Passing it in explicitly avoids potentially
crashing if this code is called from the runner.
