fix: improve error message on registration failed

[marcosvega91]

I have changed the error message that will be shown if navigator.serviceWorker.register throw an error.

Now the error shows the complete message text from error object and a tip in the case the user didn't run npx msw init <PUBLIC_DIR> in his project.

An example of message is:

[MSW] Failed to register a ServiceWorker for scope ('http://localhost:62036/') with script ('http://localhost:62036/invalidServiceWorker'): A bad HTTP response code (404) was received when fetching the script. If the worker file has not been found maybe you didn't run "npx msw init <PUBLIC_DIR>"

[marcosvega91]

I need to update the test, my stupid fault ✌️

[marcosvega91]

now is ready, let me know :)

[kettanaito]

Awesome changes, @marcosvega91! Thank you.

I've updated your feature branch, and slightly modified the error message when the worker is not found. I think it's better if we are definitely sure that the non-existing worker is the issue, and can provide a more targeted error message with instructions. All the other errors are handled using a generic error message printed to browser's console.

[kettanaito]

Thank you once more, @marcosvega91! Welcome to contributors 🎉