PHP Warning: Undefined array key “value” in lib-widget-fields.php

Title: PHP Warning: Undefined array key “value” in lib-widget-fields.php (checkbox widget field)

Plugin version: 8.8.7

Environment:

• PHP 8.3 (CloudLinux Alt-PHP)
• WordPress (latest)

Description:

The checkbox() method in includes/widgets/lib-widget-fields.php (line 85) reads $field['value'] directly without checking whether the key exists:

php

protected static function checkbox( $id, $name, $value, $label, $options, $field ) {
    ?>
    <input type="checkbox" ... value="<?php echo esc_attr( $field['value'] ); ?>" <?php checked( $value, $field['value'] ); ?> />

However, several built-in widgets define checkbox-type fields without setting a 'value' key, e.g.:

• includes/widgets/popular-listings.php
• includes/widgets/submit-listing.php
• includes/widgets/login-form.php
• includes/widgets/featured-listing.php
• includes/widgets/all-locations.php

Whenever one of these widgets is rendered in the WordPress admin (widget editor / Customizer), it throws:

PHP Warning: Undefined array key "value" in .../includes/widgets/lib-widget-fields.php on line 85

This occurred 40 times in our error log over roughly a week of normal admin usage.

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