save_post Error Reporting Boilerplate

admin-notice-hook.php

add_action( 'admin_notices', 'my_error_messages' );

save-post-hook.php

add_action( 'save_post', 'my_save_post_function' );
function my_save_function( $post_id ) {
    $error = false;

    // Do stuff.

    if ($something_went_wrong) {
        $error = $result;        
    }

    if ($error) {
        return $error;
    }

    return true;
}