Make get_src return nullable

Author: sirreal

src/wp-includes/class-wp-script-modules.php

@@ -231,10 +231,15 @@ public function add_hooks() {
 	 */
 	public function print_enqueued_script_modules() {
 		foreach ( $this->get_marked_for_enqueue() as $id => $script_module ) {
+			$src = $this->get_src( $id );
+			if ( null === $src ) {
+				continue;
+			}
+
 			wp_print_script_tag(
 				array(
 					'type' => 'module',
-					'src'  => $this->get_src( $id ),
+					'src'  => $src,
 					'id'   => $id . '-js-module',
 				)
 			);
@@ -251,11 +256,16 @@ public function print_enqueued_script_modules() {
 	 */
 	public function print_script_module_preloads() {
 		foreach ( $this->get_dependencies( array_keys( $this->get_marked_for_enqueue() ), array( 'static' ) ) as $id => $script_module ) {
+			$src = $this->get_src( $id );
+			if ( null === $src ) {
+				continue;
+			}
+
 			// Don't preload if it's marked for enqueue.
 			if ( true !== $script_module['enqueue'] ) {
 				echo sprintf(
 					'<link rel="modulepreload" href="%s" id="%s">',
-					esc_url( $this->get_src( $id ) ),
+					esc_url( $src ),
 					esc_attr( $id . '-js-modulepreload' )
 				);
 			}
@@ -293,7 +303,11 @@ private function get_import_map(): array {
 		$imports           = array();
 		$script_module_ids = array_unique( array_keys( $this->exposed ) + array_keys( $this->get_marked_for_enqueue() ) );
 		foreach ( $this->get_dependencies( $script_module_ids ) as $id => $script_module ) {
-			$imports[ $id ] = $this->get_src( $id );
+			$src = $this->get_src( $id );
+			if ( null === $src ) {
+				continue;
+			}
+			$imports[ $id ] = $src;
 		}
 		return array( 'imports' => $imports );
 	}
@@ -360,11 +374,11 @@ function ( $dependency_script_modules, $id ) use ( $import_types ) {
 	 * @since 6.5.0
 	 *
 	 * @param string $id The script module identifier.
-	 * @return string The script module src with a version if relevant.
+	 * @return string|null The script module src with a version if relevant.
 	 */
-	private function get_src( string $id ): string {
+	private function get_src( string $id ): ?string {
 		if ( ! isset( $this->registered[ $id ] ) ) {
-			return '';
+			return null;
 		}
 
 		$script_module = $this->registered[ $id ];