Scripts: Prevent react-refresh/runtime from being externalized in HMR mode

[theritiktiwari]

What?

Closes #77293

Prevent react-refresh/runtime from being externalized by DependencyExtractionWebpackPlugin during HMR mode.

This ensures the generated *.asset.php file does not include the wp-react-refresh-runtime dependency, which is not registered by WordPress and causes block scripts to fail in development mode.

Why?

When running block development with HMR (npx wp-scripts start --hot), ReactRefreshWebpackPlugin injects and manages react-refresh/runtime internally.

However, DependencyExtractionWebpackPlugin was externalizing this runtime dependency and generating:

'dependencies' => array(
    ...
    'wp-react-refresh-runtime',
)

Since WordPress never registers a corresponding wp-react-refresh-runtime script handle, the editor attempts to enqueue a missing dependency, causing the block script to fail to load during development.

This issue only affects HMR/development mode.

How?

Pass a custom requestToExternal override to DependencyExtractionWebpackPlugin when React Fast Refresh is enabled. The override prevents react-refresh/runtime from being externalized. This keeps the runtime managed entirely by ReactRefreshWebpackPlugin and prevents invalid WordPress script dependencies from being generated.

Testing Instructions

1. Create a block plugin using @wordpress/create-block.
2. Start the development server in HMR mode.
3. Open the block editor.
4. Before applying this PR, inspect the generated *.asset.php file and observe wp-react-refresh-runtime inside the dependencies array.
5. Apply this PR and rebuild/start again.
6. Verify the generated *.asset.php file no longer includes wp-react-refresh-runtime.
7. Confirm the block loads correctly in the editor without missing script dependency errors.

Testing Instructions for Keyboard

1. Open the block editor using the keyboard only.
2. Insert the test block.
3. Verify the editor loads correctly and the block is usable.
4. Confirm there are no missing dependency errors preventing interaction.

Use of AI Tools

Used GH Copilot for assistance with debugging, and drafting PR documentation.

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Co-authored-by: theritiktiwari <theritiktiwari@git.wordpress.org>
Co-authored-by: karthikeya-io <karthikeya01@git.wordpress.org>

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[github-actions]

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