Build/Tests: Ensure set_error_handler is cleaned up.

Follow up to: [57332].

Fixes #60305.



git-svn-id: https://develop.svn.wordpress.org/trunk@57361 602fd350-edb4-49c9-b593-d223f7449a82

tests/phpunit/tests/theme/wpThemeJson.php

@@ -4304,6 +4304,9 @@ static function ( $errno, $errstr ) {
 		);
 
 		$theme_json->set_spacing_sizes();
+
+		restore_error_handler();
+
 		$this->assertSame( $expected_output, _wp_array_get( $theme_json->get_raw_data(), array( 'settings', 'spacing', 'spacingSizes', 'default' ) ) );
 	}