Image editor: fatal error when attachment metadata has no `sizes` array

[josephscott]

I noticed some fatal errors in wp_save_image() on a site recently.

Uncaught TypeError: array_merge(): Argument #1 must be of type array, null given

That came from this line - ​https://github.com/WordPress/wordpress-develop/blame/trunk/src/wp-admin/includes/image-edit.php#L1132

$meta['sizes'] = array_merge( $meta['sizes'], $img->multi_resize( $_sizes ) );

While I suspect this is something wrong or a mistake with the image, after looking at the code WordPress needs to make sure that $meta['sizes'] exists before using it.

There is a similar issue with wp_restore_image().

https://core.trac.wordpress.org/ticket/65748

AI assistance: Yes
Tool(s): Claude
Model(s): Opus 5
Used for: Writing the tests

## Test Report
Patch tested: ​https://github.com/WordPress/wordpress-develop/pull/12744

### Environment

• WordPress: 7.1-beta3-20260728.201755
• Subdirectory: No
• PHP: 7.4.33
• Server: PHP.wasm
• Database: WP_SQLite_Driver (Server: 8.0.38 / Client: 3.51.0)
• Browser: Chrome 150.0.0.0
• OS: macOS
• Theme: Twenty Twenty-Five 1.5
• MU Plugins: None activated
• Plugins:
  • Test Reports 1.3.0

### Steps taken

1. Launched the WordPress Playground instance built from PR #12744.
2. Navigated to Media → Library and uploaded a test image.
3. Clicked Edit Image to open the core image editor interface.
4. Performed Crop and Scale operations, then saved the modifications.
5. Clicked Restore Original Image to revert the image back to its original state.
6. Verified that no PHP fatal errors or warnings occurred during the process.
7. ✅ Patch is solving the problem

### Expected result

• Image saving, cropping, scaling, and restoring operations should execute successfully without throwing PHP type errors or fatal errors when processing attachment metadata.

### Additional Notes

• Tested via WordPress Playground instance. Crop, scale, and restore functionalities work as expected without any errors.

### Screenshots/Screencast with results

• Screenshot/Screencast before: N/A
• Screenshot/Screencast after: N/A

### Support Content

• PR URL: ​https://github.com/WordPress/wordpress-develop/pull/12744
• Trac Ticket: https://core.trac.wordpress.org/ticket/65748