Quite a few PHP Errors and Warnings

Hi,
Was testing this plugin out on my local dev environment and when I click published to create my first help item I got the following PHP Errors/Warnings:

Notice: Undefined variable: post_id in /wp-content/plugins/cm-onboarding/backend/cm-on-boarding-backend.php on line 678

Warning: Cannot modify header information – headers already sent by (output started at /wp-content/plugins/cm-onboarding/backend/cm-on-boarding-backend.php:678)

The help item post did save however, as I later discovered.