fix: handle invalid package uploads

templates/admin/dashboard.php

@@ -26,6 +26,20 @@ if ( ! defined( 'ABSPATH' ) ) {
 		</p>
 	</div>
 
+	<?php // phpcs:ignore WordPress.Security.NonceVerification.Recommended -- Displays redirect status only. ?>
+	<?php if ( isset( $_GET['wpcs_import_error'] ) ) : ?>
+		<div class="notice notice-error">
+			<p><?php echo esc_html( sanitize_text_field( wp_unslash( $_GET['wpcs_import_error'] ) ) ); ?></p>
+		</div>
+	<?php endif; ?>
+
+	<?php // phpcs:ignore WordPress.Security.NonceVerification.Recommended -- Displays redirect status only. ?>
+	<?php if ( isset( $_GET['wpcs_imported'] ) ) : ?>
+		<div class="notice notice-success">
+			<p><?php echo esc_html__( 'The package JSON file was validated successfully.', 'wp-content-sync' ); ?></p>
+		</div>
+	<?php endif; ?>
+
 	<h2><?php echo esc_html__( 'Current Defaults', 'wp-content-sync' ); ?></h2>
 	<table class="widefat striped">
 		<tbody>