wp-includes/class-wp-error.php:140Gets a single error message.
$codestring|intoptional''string public function get_error_message( $code = '' ) { if ( empty( $code ) ) { $code = $this->get_error_code(); } $messages = $this->get_error_messages( $code ); if ( empty( $messages ) ) { return ''; } return $messages[0]; }Introduced in 2.1.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/class-wp-error.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.