Media: guard attachment icon size lookup

[dhrupo]

Summary

Guard the icon fallback path in wp_get_attachment_image_src() when wp_getimagesize() cannot read the icon file.

Problem

When wp_get_attachment_image_src() falls back to a mime type icon, it assumes wp_getimagesize() returns an array and immediately reads width and height from it. If the icon file cannot be read, PHP 8.5 surfaces incorrect array access on that falsey return value.

Trac ticket: https://core.trac.wordpress.org/ticket/64742

Solution

Store the result of wp_getimagesize() first and only read width and height when it returns an array. This preserves the existing false return behavior when the icon dimensions cannot be determined.

Testing

Added a PHPUnit regression test that forces the mime type icon path to point at a missing icon file and verifies wp_get_attachment_image_src() returns false cleanly.

Verified in the configured local wordpress-develop environment with:

• node ./tools/local-env/scripts/docker.js exec --user wp_php php ./vendor/bin/phpunit --filter test_wp_get_attachment_image_src_with_icon_when_icon_file_size_cannot_be_read tests/phpunit/tests/media.php
• node ./tools/local-env/scripts/docker.js exec --user wp_php php ./vendor/bin/phpunit --filter 'test_wp_get_attachment_image_(url|src_with_icon_when_icon_file_size_cannot_be_read)' tests/phpunit/tests/media.php

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[github-actions]

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