Fix translation loaded too early (#124)

Author: tfirdaus

app/Features/MaintenanceMode.php

@@ -25,6 +25,18 @@ final class MaintenanceMode implements Hookable
 	public function hook(Hook $hook): void
 	{
 		$hook->addFilter(Option::hook('sanitize:site_maintenance_args'), [$this, 'sanitizeArgsOption'], PHP_INT_MAX);
+		$hook->addFilter(Option::hook('default:site_maintenance_args'), static function (): array {
+			return [
+				'headline' => __(
+					'Under Maintenance 🚧',
+					'syntatis-feature-flipper',
+				),
+				'message' => __(
+					'We are currently performing some scheduled maintenance. We will be back as soon as possible.',
+					'syntatis-feature-flipper',
+				),
+			];
+		}, PHP_INT_MAX);
 
 		if (Option::get('site_access') !== 'maintenance') {
 			return;

inc/settings/all.php

@@ -148,16 +148,16 @@
 				'message' => ['type' => 'string'],
 			],
 		])
-		->withDefault([
-			'headline' => __(
-				'Under Maintenance 🚧',
-				'syntatis-feature-flipper',
-			),
-			'message' => __(
-				'We are currently performing some scheduled maintenance. We will be back as soon as possible.',
-				'syntatis-feature-flipper',
-			),
-		]),
+		/**
+		 * The default requires translatable string values for the `headline` and
+		 * `message` properties. The default value will be set via the filter.
+		 * Otherwise, it will throw an error due to the translations called
+		 * too early.
+		 *
+		 * @see app/Features/MaintenanceMode.php#L28
+		 * @see https://github.com/WordPress/WordPress/blob/master/wp-includes/l10n.php#L1371-L1380
+		 */
+		->withDefault(null),
 
 	// Site: Assets.
 	(new Setting('emojis', 'boolean'))