Media: Fix animated GIF to video conversion failing due to missing import map entry

[adamsilverstein]

What

Fixes animated GIF to video conversion, which currently fails silently everywhere client-side media processing runs (block editor included): no animated_video companion is created, and the console shows:

[video-conversion] GIF to video conversion failed: TypeError: Failed to resolve module specifier '@wordpress/video-conversion/worker'

Why

Two separate bugs prevent upload-media.js from lazily importing the conversion worker:

1. wp_set_client_side_media_processing_flag() clobbers the import map. It calls wp_scripts()->add_data( 'wp-upload-media', 'module_dependencies', array( '@wordpress/vips/worker' ) ) on every admin request. add_data() overwrites rather than merges, wiping the module_dependencies already registered from script-loader-packages.php - which include both @wordpress/vips/worker and @wordpress/video-conversion/worker. The call was harmlessly redundant when introduced in [62428] (the packages file only declared the vips worker then) and became destructive when the video-conversion dependency landed in the asset file. With the entry missing from the import map, the dynamic import() throws. Since the packages registration already handles this correctly, the call is simply removed.

2. The unminified video-conversion/worker.js is never shipped. Like the VIPS modules, the Gutenberg build only produces worker.min.js (the file is large inlined worker code with no debugging value), but wp_default_script_modules() only special-cases vips/ to always use the minified file. With SCRIPT_DEBUG enabled, the import map pointed at a non-existent worker.js and the import 404ed. The existing vips condition is extended to cover video-conversion/worker.js.

Testing

Manually verified on trunk (Chrome, cross-origin isolated via Document-Isolation-Policy):

Before: uploading an animated GIF logs the module-specifier TypeError (plus a secondary blob: ... ERR_FILE_NOT_FOUND error), and the attachment's media_details has no animated_video.

After: the same upload completes with no console errors, the import map contains both workers, and the attachment gains animated_video: <name>.mp4 and animated_video_poster: <name>.jpeg, with both companion files sideloaded to the uploads directory.

Includes PHPUnit coverage (--group 65664):

• test_set_flag_preserves_upload_media_module_dependencies() asserts wp_set_client_side_media_processing_flag() leaves the upload-media script's module_dependencies untouched and that both workers are present. Verified to fail against the pre-fix code (the dependency list collapses to just the vips worker) and pass with the fix.
• test_default_script_module_files_exist() asserts every default script module resolves to an existing file for both SCRIPT_DEBUG variants, so a minified-only module can no longer be registered with a non-existent non-minified URL.

Both full test files pass (25 + 108 tests); php -l and PHPCS pass on all changed files.

Commit message

Media: Fix animated GIF to video conversion module loading.

Fix an issue with animated GIF conversion where the conversion worker could not be resolved from the script modules import map. `wp_set_client_side_media_processing_flag()` re-declared the `wp-upload-media` module dependencies via `WP_Scripts::add_data()`, which overwrites rather than merges, wiping the `@wordpress/video-conversion/worker` entry already registered from the packages asset file.  

Additionally, only a minified build of the video-conversion worker is shipped, so with `SCRIPT_DEBUG` enabled the import map pointed at a non-existent `worker.js`. The always-minified exception in `wp_default_script_modules()` is extended from the vips modules to also cover `video-conversion/worker.js`.

Follow-up to [62428].

Props andrewserong, swissspidy.
Fixes #65664.

Trac ticket: https://core.trac.wordpress.org/ticket/65664

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Props adamsilverstein, andrewserong, swissspidy.

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[andrewserong]

Good catch! This is testing nicely for me on a local checkout, thanks for the explanations in the PR description 👍

Adding the video-conversion worker to the list in script-modules.php makes sense for now. I suppose if we ever grow this list we could abstract the concept somehow, but for the scope of client-side media processing I doubt we'll ever really have more than vips + video-conversion? And if we do want to proposed more worker / skipping non-minified build features, then I reckon we could revisit then.

LGTM!

[adamsilverstein]

Closed in https://core.trac.wordpress.org/changeset/62807