Scripts: coerce live reload port to integer

[emilio-martinez]

Description

Attempting to use process.env.WP_LIVE_RELOAD_PORT was not working for me. After some debugging, I realized webpack-livereload-plugin must not expect to receive a port argument of a string type, failing silently to take the desired port, and per process.env docs:

Assigning a property on process.env will implicitly convert the value to a string.

Additionally, the use of the logical OR operator would prevent passing a 0 value, precluding the use of the following webpack-livereload-plugin functionality:

If you define port 0, an available port will be searched for, starting from 35729.

This PR aims to remedy this by parsing process.env.WP_LIVE_RELOAD_PORT before passing the value to webpack-livereload-plugin.

How has this been tested?

Validated by running these changes against a local project. Before the change, running wp-scripts start would always log one of the two below:

• Live Reload listening on port 35729
• Live Reload disabled: listen EADDRINUSE: address already in use :::35729 (for parallel processes run)

After the changes in this PR, the appropriate port will be used — including the use of a 0 value.

Types of changes

Bug fix (non-breaking change which fixes an issue)

Checklist:

• My code is tested.
• My code follows the WordPress code style.
• My code follows the accessibility standards.
• I've tested my changes with keyboard and screen readers.
• My code has proper inline documentation.
• I've included developer documentation if appropriate.
• I've updated all React Native files affected by any refactorings/renamings in this PR.

[github-actions]

👋 Thanks for your first Pull Request and for helping build the future of Gutenberg and WordPress, @emilio-martinez! In case you missed it, we'd love to have you join us in our Slack community, where we hold regularly weekly meetings open to anyone to coordinate with each other.

If you want to learn more about WordPress development in general, check out the Core Handbook full of helpful information.

[gziolo]

Thank you for your contribution. The proposed change makes sense. I had only a minor styling comment.

Side note: Live reload will eventually get replaced by React Fast Refresh as explored in #28273.

[gziolo]

Nice, it's ready to go. Thank you!

[github-actions]

Congratulations on your first merged pull request, @emilio-martinez! We'd like to credit you for your contribution in the post announcing the next WordPress release, but we can't find a WordPress.org profile associated with your GitHub account. When you have a moment, visit the following URL and click "link your GitHub account" under "GitHub Username" to link your accounts:

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Kudos!