oEmbed: Prevent PHP warnings when a registered provider is malformed

[tbradsha]

Proposed changes

There was a site generating about 10% of Jetpack-related PHP warnings on WP Cloud, all looking like this:

PHP Warning: Undefined array key 0 in /wordpress/plugins/jetpack/15.8-a.1/_inc/lib/class.media-extractor.php on line 352
PHP Warning: Undefined array key 1 in /wordpress/plugins/jetpack/15.8-a.1/_inc/lib/class.media-extractor.php on line 352

As it turned out, they had a plugin that was registering the oEmbed providers like so:

 [provider_key] => Array
    (
        [url] => some_url_regex
        [endpoint] => https://some_site/api/oembed
    )

Instead, it should have been like this:

[some_url_regex] => Array
    (
        [0] => https://some_site/api/oembed
        [1] => 1
    )

This PR adds a continue if index 0 is not set, and uses false for index 1 if not set.

Related product discussion/links

Does this pull request change what data or activity we track or use?

Testing instructions

First, add an mu-plugin:

add_filter(
	'oembed_providers',
	function ( $providers ) {
		$providers['bad_provider'] = array(
			'url'      => '#https?://example\.site/.*#i',
			'endpoint' => 'https://example.site/api/oembed',
		);
		return $providers;
	}
);

1. Go to a new post page.
2. Paste a URL that doesn't have an oEmbed, e.g. https://en.wikipedia.org/wiki/Rickrolling
3. Do NOT click "Convert to link".
4. Save the post.
5. Visit the post on the front end.

On `trunk, you'll get an error from Jetpack. On this branch you will not.

Note that refreshing the editor will show a warning from Core; that's reported here:
https://core.trac.wordpress.org/ticket/65068

[github-actions]

Are you an Automattician? Please test your changes on all WordPress.com environments to help mitigate accidental explosions.

• To test on WoA, go to the Plugins menu on a WoA dev site. Click on the "Upload" button and follow the upgrade flow to be able to upload, install, and activate the Jetpack Beta plugin. Once the plugin is active, go to Jetpack > Jetpack Beta, select your plugin (Jetpack), and enable the fix/jetpack/prevent_warnings_with_malformed_oembed_providers branch.
• To test on Simple, run the following command on your sandbox:

bin/jetpack-downloader test jetpack fix/jetpack/prevent_warnings_with_malformed_oembed_providers

Interested in more tips and information?

• In your local development environment, use the jetpack rsync command to sync your changes to a WoA dev blog.
• Read more about our development workflow here: PCYsg-eg0-p2
• Figure out when your changes will be shipped to customers here: PCYsg-eg5-p2

[github-actions]

Thank you for your PR!

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---

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Jetpack plugin:

The Jetpack plugin has different release cadences depending on the platform:

• WordPress.com Simple releases happen as soon as you deploy your changes after merging this PR (PCYsg-Jjm-p2).
• WoA releases happen weekly.
• Releases to self-hosted sites happen monthly:
  • Scheduled release: May 5, 2026
  • Code freeze: May 4, 2026

If you have any questions about the release process, please ask in the #jetpack-releases channel on Slack.

[jp-launch-control]

Code Coverage Summary

Coverage changed in 1 file.

File	Coverage	Δ%	Δ Uncovered
projects/plugins/jetpack/_inc/lib/class.media-extractor.php	209/245 (85.31%)	-0.29%	1 ❤️‍🩹

Full summary · PHP report · JS report

[anomiex]

Seems reasonable. Haven't tested.