Dynamo .dyn file crashing Revit 2018

I have created a dynamo script (see below) that is meant as a project startup to automate/prompt the user the input certain settings. I am quite new to Dynamo so please be kind on the lack of any eloquent scripting.

However, when I open Revit 2018, Dynamo, and then the .dyn file, Revit crashes. For Revit 2019 I do not have this problem. Am I using a node/package that is not allowable for Revit 2018? Or is my script being improperly laid out?

Let me know.