From ad51bbf1a344de15a55c7036074973e8f19d5a6f Mon Sep 17 00:00:00 2001
From: Nate Allen <nate.allen@automattic.com>
Date: Thu, 19 Mar 2026 10:19:58 -0400
Subject: [PATCH 1/3] REST API: Restore `is_array()` check in
 `rest_convert_error_to_response()`.

The null coalescing conversion in [61429] removed the `is_array()` guard
when accessing `$error_data['status']`. Since `WP_Error` data can be any
type (including `stdClass`), this causes a PHP fatal error when non-array
data is passed.

This restores the type check while still using null coalescing for the
array case.

Props costdev, westonruter.
Fixes #64901. See #63430.
---
 src/wp-includes/rest-api.php                 |  2 +-
 tests/phpunit/tests/rest-api/rest-server.php | 13 +++++++++++++
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/src/wp-includes/rest-api.php b/src/wp-includes/rest-api.php
index cb6833772a765..50b25690f1f6c 100644
--- a/src/wp-includes/rest-api.php
+++ b/src/wp-includes/rest-api.php
@@ -3428,7 +3428,7 @@ function rest_convert_error_to_response( $error ) {
 	$status = array_reduce(
 		$error->get_all_error_data(),
 		static function ( $status, $error_data ) {
-			return $error_data['status'] ?? $status;
+			return is_array( $error_data ) ? ( $error_data['status'] ?? $status ) : $status;
 		},
 		500
 	);
diff --git a/tests/phpunit/tests/rest-api/rest-server.php b/tests/phpunit/tests/rest-api/rest-server.php
index 692c363ac7595..bd3a9346f70b2 100644
--- a/tests/phpunit/tests/rest-api/rest-server.php
+++ b/tests/phpunit/tests/rest-api/rest-server.php
@@ -592,6 +592,19 @@ public function test_error_to_response_with_additional_data() {
 		$this->assertSame( array( array( 'status' => 400 ) ), $response->get_data()['additional_data'] );
 	}
 
+	/**
+	 * @ticket 64901
+	 */
+	public function test_error_to_response_with_stdclass_data() {
+		$error = new WP_Error( 'test', 'test', (object) array( 'status' => 400 ) );
+
+		$response = rest_convert_error_to_response( $error );
+		$this->assertInstanceOf( 'WP_REST_Response', $response );
+
+		// stdClass data should not cause a fatal, status should default to 500.
+		$this->assertSame( 500, $response->get_status() );
+	}
+
 	public function test_rest_error() {
 		$data     = array(
 			'code'    => 'wp-api-test-error',

From e0601390152c7d1affa32f9f846695cdeb30f18d Mon Sep 17 00:00:00 2001
From: Nate Allen <nate.allen@automattic.com>
Date: Thu, 19 Mar 2026 10:21:24 -0400
Subject: [PATCH 2/3] Revert to original isset() ternary instead of null
 coalescing with is_array().

---
 src/wp-includes/rest-api.php | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/wp-includes/rest-api.php b/src/wp-includes/rest-api.php
index 50b25690f1f6c..fe99e416f2387 100644
--- a/src/wp-includes/rest-api.php
+++ b/src/wp-includes/rest-api.php
@@ -3428,7 +3428,7 @@ function rest_convert_error_to_response( $error ) {
 	$status = array_reduce(
 		$error->get_all_error_data(),
 		static function ( $status, $error_data ) {
-			return is_array( $error_data ) ? ( $error_data['status'] ?? $status ) : $status;
+			return is_array( $error_data ) && isset( $error_data['status'] ) ? $error_data['status'] : $status;
 		},
 		500
 	);

From d88933d6dc2dbfb75e403993b27e1a6c918a14a7 Mon Sep 17 00:00:00 2001
From: Nate Allen <nate.allen@automattic.com>
Date: Thu, 19 Mar 2026 12:27:49 -0400
Subject: [PATCH 3/3] Add inline comment explaining the is_array() check.

---
 src/wp-includes/rest-api.php | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/wp-includes/rest-api.php b/src/wp-includes/rest-api.php
index fe99e416f2387..b97dfd014be41 100644
--- a/src/wp-includes/rest-api.php
+++ b/src/wp-includes/rest-api.php
@@ -3428,6 +3428,7 @@ function rest_convert_error_to_response( $error ) {
 	$status = array_reduce(
 		$error->get_all_error_data(),
 		static function ( $status, $error_data ) {
+			// Note: $error_data may not be an array (e.g. stdClass), so is_array() check is intentional.
 			return is_array( $error_data ) && isset( $error_data['status'] ) ? $error_data['status'] : $status;
 		},
 		500