WP_Error::add_data( mixed $data, string|int $code = '' )

Source

File: wp-includes/class-wp-error.php

public function add_data( $data, $code = '' ) {
		if ( empty( $code ) ) {
			$code = $this->get_error_code();
		}

		if ( isset( $this->error_data[ $code ] ) ) {
			$this->additional_data[ $code ][] = $this->error_data[ $code ];
		}

		$this->error_data[ $code ] = $data;
	}