So, I’m completely new to this, but I’m trying to get my Postmarks site up & running. Unfortunately, I just see error messages (See screenshot. Ignore the red mark, that was an accident. 
). Can someone please point me in the right direction?
see the section for “secret” in their docs express-session - npm
there’s a place where you set up a session middleware, and you give it an options object. that object needs to have a secret field added. the docs section has advice on how to set this correctly and how to manage the actual secret value safely