Creation of dynamic property CbtZipArchive::$theme_folder is deprecated

[23-Dec-2023 02:56:13 UTC] PHP Deprecated:  Creation of dynamic property CbtZipArchive::$theme_folder is deprecated in /var/www/html/wp-content/p
lugins/create-block-theme/admin/create-theme/cbt-zip-archive.php on line 14
[23-Dec-2023 02:56:13 UTC] PHP Stack trace:
[23-Dec-2023 02:56:13 UTC] PHP   1. {main}() /var/www/html/wp-admin/themes.php:0
[23-Dec-2023 02:56:13 UTC] PHP   2. require_once() /var/www/html/wp-admin/themes.php:10
[23-Dec-2023 02:56:13 UTC] PHP   3. do_action($hook_name = 'admin_init') /var/www/html/wp-admin/admin.php:175
[23-Dec-2023 02:56:13 UTC] PHP   4. WP_Hook->do_action($args = [0 => '']) /var/www/html/wp-includes/plugin.php:517
[23-Dec-2023 02:56:13 UTC] PHP   5. WP_Hook->apply_filters($value = '', $args = [0 => '']) /var/www/html/wp-includes/class-wp-hook.php:348
[23-Dec-2023 02:56:13 UTC] PHP   6. Create_Block_Theme_Admin->blockbase_save_theme('') /var/www/html/wp-includes/class-wp-hook.php:324
[23-Dec-2023 02:56:13 UTC] PHP   7. Create_Block_Theme_Admin->create_child_theme($theme = ['type' => 'child', 'variation' => '', 'name' => 'Recommendations Twenty Twenty Four Child', 'description' => '', 'uri' => '', 'author' => 'Ben Keith', 'author_uri' => '', 'image_credits' => '', 'recommended_plugins' => '', 'tags-subject' => [0 => 'blog', 1 => 'news', 2 => 'portfolio'], 'tags-layout' => [0 => 'one-column', 1 => 'wide-blocks'], 'tags-features' => [0 => 'accessibility-ready', 1 => 'block-patterns', 2 => 'block-styles', 3 => 'custom-colors', 4 => 'custom-logo', 5 => 'custom-menu', 6 => 'editor-style', 7 => 'featured-images', 8 => 'full-site-editing', 9 => 'rtl-language-support', 10 => 'sticky-post', 11 => 'style-variations', 12 => 'threaded-comments', 13 => 'translation-ready'], 'tags_custom' => ''], $screenshot = ['name' => '', 'full_path' => '', 'type' => '', 'tmp_name' => '', 'error' => 4, 'size' => 0]) /var/www/html/wp-content/plugins/create-block-theme/admin/class-create-theme.php:470
[23-Dec-2023 02:56:13 UTC] PHP   8. Theme_Zip::create_zip($filename = '/tmp/recommendationstwentytwentyfourchild27ojba') /var/www/html/wp-content/plugins/create-block-theme/admin/class-create-theme.php:264
[23-Dec-2023 02:56:13 UTC] PHP   9. CbtZipArchive->__construct($theme_slug = 'recommendationstwentytwentyfourchild') /var/www/html/wp-content/plugins/create-block-theme/admin/create-theme/theme-zip.php:21

This warning appears in the log when creating a child theme with WP 6.4.2 on PHP 8.2, using 10up’s

If WP_DEBUG_DISPLAY is true, that error message is output before the ZIP file’s headers:

[23-Dec-2023 02:50:24 UTC] PHP Warning:  Cannot modify header information - headers already sent by (output started at /var/www/html/wp-content/plugins/creat
e-block-theme/admin/create-theme/cbt-zip-archive.php:14) in /var/www/html/wp-content/plugins/create-block-theme/admin/class-create-theme.php on line 291
[23-Dec-2023 02:50:24 UTC] PHP Stack trace:
[23-Dec-2023 02:50:24 UTC] PHP   1. {main}() /var/www/html/wp-admin/themes.php:0
[23-Dec-2023 02:50:24 UTC] PHP   2. require_once() /var/www/html/wp-admin/themes.php:10
[23-Dec-2023 02:50:24 UTC] PHP   3. do_action($hook_name = 'admin_init') /var/www/html/wp-admin/admin.php:175
[23-Dec-2023 02:50:24 UTC] PHP   4. WP_Hook->do_action($args = [0 => '']) /var/www/html/wp-includes/plugin.php:517
[23-Dec-2023 02:50:24 UTC] PHP   5. WP_Hook->apply_filters($value = '', $args = [0 => '']) /var/www/html/wp-includes/class-wp-hook.php:348
[23-Dec-2023 02:50:24 UTC] PHP   6. Create_Block_Theme_Admin->blockbase_save_theme('') /var/www/html/wp-includes/class-wp-hook.php:324
[23-Dec-2023 02:50:24 UTC] PHP   7. Create_Block_Theme_Admin->create_child_theme($theme = ['type' => 'child', 'variation' => '', 'name' => 'Recommendations T
wenty Twenty Four', 'description' => '', 'uri' => '', 'author' => 'Ben Keith', 'author_uri' => '', 'image_credi
ts' => '', 'recommended_plugins' => '', 'tags-subject' => [0 => 'blog', 1 => 'news', 2 => 'portfolio'], 'tags-layout' => [0 => 'one-column', 1 => 'wide-block
s'], 'tags-features' => [0 => 'accessibility-ready', 1 => 'block-patterns', 2 => 'block-styles', 3 => 'custom-colors', 4 => 'custom-logo', 5 => 'custom-menu'
, 6 => 'editor-style', 7 => 'featured-images', 8 => 'full-site-editing', 9 => 'rtl-language-support', 10 => 'sticky-post', 11 => 'style-variations', 12 => 't
hreaded-comments', 13 => 'translation-ready'], 'tags_custom' => ''], $screenshot = ['name' => '', 'full_path' => '', 'type' => '', 'tmp_name' => '', 'error' 
=> 4, 'size' => 0]) /var/www/html/wp-content/plugins/create-block-theme/admin/class-create-theme.php:470
[23-Dec-2023 02:50:24 UTC] PHP   8. header($header = 'Content-Type: application/zip') /var/www/html/wp-content/plugins/create-block-theme/admin/class-create-
theme.php:291

Outputting the error message before the header is output in turn breaks the ZIP file output, because the header() call comes after the error message has been printed. Instead of downloading a ZIP, the ZIP’s contents are displayed as a large amount of mojibake in an HTML file.