Cannot make a mongodb connection

I am new to mongoDB. I am a student trying to complete an exercise. I need to connect to a mongo database and seed that database with starter data. There is more to the project but I will tackle that when I get the connection/seeding problem solved.

Here are the environment particulars:

• mongo -- version 3.6.2 installed with brew
• macOSX High Sierra 10.13.3
• app written in node/express
• seeder is the npm package used for seeding (in theory anyway)
• IDE -- VSCode using Integrated Terminal as a CLI
• Just for thoroughness, restarted mongo by brew services restart mongodb
• start script = npm start ("nodemon ./start")
• link to the gist file: https://gist.github.com/dhawkinson/374e6e4cb79fb1eb2b8db11ede2af4b3

I get the following two console.logs

Express server is listening on port 5000
courseRatingDB connection established

which you can see in the gist, but I get nothing else, no errors thrown, no syntax errors, no connection, no seeding. Can anyone tell me why, and how to fix it?