1. Format the code.

2. Don't use variable filter name. Pass the ditor_name as the second parameter.

lib/editor-settings.php

@@ -83,7 +83,7 @@ function gutenberg_initialize_editor( $editor_name, $editor_script_handle, $sett
 	 *
 	 * @param Array $preload_data Array containing the preloaded data.
 	 */
-	$preload_data = apply_filters( "{$editor_name}_preload_data", $preload_data );
+	$preload_data = apply_filters( 'block_editor_preload_data', $preload_data, $editor_name );
 
 	wp_add_inline_script(
 		'wp-api-fetch',

lib/navigation-page.php

@@ -148,17 +148,20 @@ function gutenberg_navigation_editor_load_block_editor_scripts_and_styles( $is_b
  * This function removes menu-related data from the "common" preloading middleware and calls
  * createMenuPreloadingMiddleware middleware because we need to use custom preloading logic for menus.
  *
- * @param Array $preload_data Array containing the preloaded data.
+ * @param Array  $preload_data Array containing the preloaded data.
+ * @param string $context Current editor name.
  * @return array Filtered preload data.
  */
-function gutenberg_navigation_editor_preload_menus( $preload_data ) {
+function gutenberg_navigation_editor_preload_menus( $preload_data, $context ) {
+	if ( 'navigation_editor' !== $context ) {
+		return $preload_data;
+	}
+
 	$menus_data_path = gutenberg_navigation_get_menus_endpoint();
-	$menus_data      = empty( $preload_data[ $menus_data_path ] ) ?
-			array()
-			:
-			array(
-				$menus_data_path => $preload_data[ $menus_data_path ],
-			);
+	$menus_data      = array();
+	if ( ! empty( $preload_data[ $menus_data_path ] ) ) {
+		$menus_data = array( $menus_data_path => $preload_data[ $menus_data_path ] );
+	}
 
 	if ( ! $menus_data ) {
 		return $preload_data;
@@ -177,4 +180,4 @@ function gutenberg_navigation_editor_preload_menus( $preload_data ) {
 	return $preload_data;
 }
 
-add_filter( 'navigation_editor_preload_data', 'gutenberg_navigation_editor_preload_menus' );
+add_filter( 'block_editor_preload_data', 'gutenberg_navigation_editor_preload_menus', 10, 2 );

phpunit/navigation-page-test.php

@@ -67,7 +67,7 @@ public function test_gutenberg_navigation_editor_preload_menus_function_returns_
 			$menus_endpoint                  => ( 'some menus' ),
 		);
 
-		$result = gutenberg_navigation_editor_preload_menus( $preload_data );
+		$result = gutenberg_navigation_editor_preload_menus( $preload_data, 'navigation_editor' );
 		$this->assertArrayHasKey( '/__experimental/menu-locations', $result );
 		$this->assertArrayHasKey( 'OPTIONS', $result );
 		$this->assertArrayNotHasKey( $menus_endpoint, $result );