Script Loader: Defer single-page admin init until DOMContentLoaded.

The Connectors and Font Library admin screens register a `-prerequisites`
classic-script handle with an empty `src` and attach an inline script that
does `import("@wordpress/boot").then(mod => mod.init(...))`. Because the
handle has no `src`, only the inline is printed, and it runs as a classic
script the moment the parser reaches it.

On fast CDN-fronted hosts (WordPress VIP, CloudFront, etc.) in Chrome,
`@wordpress/boot` is already `<link rel="modulepreload">`-ed, so the
dynamic import resolves and the module evaluates before the parser has
reached the classic deps it relies on (`wp-private-apis`, `wp-components`,
`wp-theme`). At its top-level `@wordpress/boot` reads
`window.wp.theme.privateApis`, which is still undefined at that point,
causing `unlock(undefined)` to throw "Cannot unlock an undefined object".
The mount element stays empty and `initSinglePage` / `init` never runs.

Wrap the dynamic import in `DOMContentLoaded`. The HTML spec guarantees
`DOMContentLoaded` fires only after every parser-blocking classic
`<script>` has executed, so all required globals are populated before
`@wordpress/boot` evaluates. A `document.readyState` guard preserves the
existing behavior when the inline is evaluated after DOM ready (e.g.
injected late).

Applied to all four auto-generated files that share the pattern:
 * src/wp-includes/build/pages/options-connectors/page.php
 * src/wp-includes/build/pages/options-connectors/page-wp-admin.php
 * src/wp-includes/build/pages/font-library/page.php
 * src/wp-includes/build/pages/font-library/page-wp-admin.php

Fixes #65103.

Made-with: Cursor

Author: itzmekhokan

src/wp-includes/build/pages/font-library/page-wp-admin.php

@@ -153,11 +153,21 @@ function wp_font_library_wp_admin_enqueue_scripts( $hook_suffix ) {
 		// 2. It initializes the boot module as an inline script.
 		wp_register_script( 'font-library-wp-admin-prerequisites', '', $asset['dependencies'], $asset['version'], true );
 
-		// Add inline script to initialize the app using initSinglePage (no menuItems)
+		/*
+		 * Add inline script to initialize the app using initSinglePage (no menuItems).
+		 *
+		 * The call is deferred until DOMContentLoaded so that all classic script
+		 * dependencies of @wordpress/boot (wp-private-apis, wp-components, wp-theme,
+		 * etc.) have finished parsing and executing before the dynamic module import
+		 * resolves. Without this, a modulepreloaded @wordpress/boot can win the race
+		 * against the classic-script-printing pass on fast CDN-fronted hosts in
+		 * Chrome, evaluating before wp.theme.privateApis is defined and throwing
+		 * "Cannot unlock an undefined object". See Trac #65103.
+		 */
 		wp_add_inline_script(
 			'font-library-wp-admin-prerequisites',
 			sprintf(
-				'import("@wordpress/boot").then(mod => mod.initSinglePage({mountId: "%s", routes: %s}));',
+				'(function(){var run=function(){import("@wordpress/boot").then(function(mod){mod.initSinglePage({mountId: "%s", routes: %s});});};if(document.readyState==="loading"){document.addEventListener("DOMContentLoaded",run);}else{run();}})();',
 				'font-library-wp-admin-app',
 				wp_json_encode( $routes, JSON_HEX_TAG | JSON_UNESCAPED_SLASHES )
 			)

src/wp-includes/build/pages/font-library/page.php

@@ -159,12 +159,22 @@ function wp_font_library_render_page() {
 		// 2. It initializes the boot module as an inline script.
 		wp_register_script( 'font-library-prerequisites', '', $asset['dependencies'], $asset['version'], true );
 
-		// Add inline script to initialize the app
+		/*
+		 * Add inline script to initialize the app.
+		 *
+		 * The call is deferred until DOMContentLoaded so that all classic script
+		 * dependencies of @wordpress/boot (wp-private-apis, wp-components, wp-theme,
+		 * etc.) have finished parsing and executing before the dynamic module import
+		 * resolves. Without this, a modulepreloaded @wordpress/boot can win the race
+		 * against the classic-script-printing pass on fast CDN-fronted hosts in
+		 * Chrome, evaluating before wp.theme.privateApis is defined and throwing
+		 * "Cannot unlock an undefined object". See Trac #65103.
+		 */
 		$init_modules = [];
 		wp_add_inline_script(
 			'font-library-prerequisites',
 			sprintf(
-				'import("@wordpress/boot").then(mod => mod.init({mountId: "%s", menuItems: %s, routes: %s, initModules: %s, dashboardLink: "%s"}));',
+				'(function(){var run=function(){import("@wordpress/boot").then(function(mod){mod.init({mountId: "%s", menuItems: %s, routes: %s, initModules: %s, dashboardLink: "%s"});});};if(document.readyState==="loading"){document.addEventListener("DOMContentLoaded",run);}else{run();}})();',
 				'font-library-app',
 				wp_json_encode( $menu_items, JSON_HEX_TAG | JSON_UNESCAPED_SLASHES ),
 				wp_json_encode( $routes, JSON_HEX_TAG | JSON_UNESCAPED_SLASHES ),

src/wp-includes/build/pages/options-connectors/page-wp-admin.php

@@ -153,11 +153,21 @@ function wp_options_connectors_wp_admin_enqueue_scripts( $hook_suffix ) {
 		// 2. It initializes the boot module as an inline script.
 		wp_register_script( 'options-connectors-wp-admin-prerequisites', '', $asset['dependencies'], $asset['version'], true );
 
-		// Add inline script to initialize the app using initSinglePage (no menuItems)
+		/*
+		 * Add inline script to initialize the app using initSinglePage (no menuItems).
+		 *
+		 * The call is deferred until DOMContentLoaded so that all classic script
+		 * dependencies of @wordpress/boot (wp-private-apis, wp-components, wp-theme,
+		 * etc.) have finished parsing and executing before the dynamic module import
+		 * resolves. Without this, a modulepreloaded @wordpress/boot can win the race
+		 * against the classic-script-printing pass on fast CDN-fronted hosts in
+		 * Chrome, evaluating before wp.theme.privateApis is defined and throwing
+		 * "Cannot unlock an undefined object". See Trac #65103.
+		 */
 		wp_add_inline_script(
 			'options-connectors-wp-admin-prerequisites',
 			sprintf(
-				'import("@wordpress/boot").then(mod => mod.initSinglePage({mountId: "%s", routes: %s}));',
+				'(function(){var run=function(){import("@wordpress/boot").then(function(mod){mod.initSinglePage({mountId: "%s", routes: %s});});};if(document.readyState==="loading"){document.addEventListener("DOMContentLoaded",run);}else{run();}})();',
 				'options-connectors-wp-admin-app',
 				wp_json_encode( $routes, JSON_HEX_TAG | JSON_UNESCAPED_SLASHES )
 			)

src/wp-includes/build/pages/options-connectors/page.php

@@ -159,12 +159,22 @@ function wp_options_connectors_render_page() {
 		// 2. It initializes the boot module as an inline script.
 		wp_register_script( 'options-connectors-prerequisites', '', $asset['dependencies'], $asset['version'], true );
 
-		// Add inline script to initialize the app
+		/*
+		 * Add inline script to initialize the app.
+		 *
+		 * The call is deferred until DOMContentLoaded so that all classic script
+		 * dependencies of @wordpress/boot (wp-private-apis, wp-components, wp-theme,
+		 * etc.) have finished parsing and executing before the dynamic module import
+		 * resolves. Without this, a modulepreloaded @wordpress/boot can win the race
+		 * against the classic-script-printing pass on fast CDN-fronted hosts in
+		 * Chrome, evaluating before wp.theme.privateApis is defined and throwing
+		 * "Cannot unlock an undefined object". See Trac #65103.
+		 */
 		$init_modules = [];
 		wp_add_inline_script(
 			'options-connectors-prerequisites',
 			sprintf(
-				'import("@wordpress/boot").then(mod => mod.init({mountId: "%s", menuItems: %s, routes: %s, initModules: %s, dashboardLink: "%s"}));',
+				'(function(){var run=function(){import("@wordpress/boot").then(function(mod){mod.init({mountId: "%s", menuItems: %s, routes: %s, initModules: %s, dashboardLink: "%s"});});};if(document.readyState==="loading"){document.addEventListener("DOMContentLoaded",run);}else{run();}})();',
 				'options-connectors-app',
 				wp_json_encode( $menu_items, JSON_HEX_TAG | JSON_UNESCAPED_SLASHES ),
 				wp_json_encode( $routes, JSON_HEX_TAG | JSON_UNESCAPED_SLASHES ),