The error message is pretty self-explanatory. It’s not a bug, it’s a scenario where your setup isn’t complete and the dotenv module won’t let you start the server until you fix it.
Basically, we store secrets in an .env file which is not committed to source control. So we also commit an .env.example file which has all the keys but no values. This is so a new developer can see what secrets they need to define for the app to run. When a server starts, the dotenv module looks to see if you have keys in your .env.example file which are not present in you .env file and alerts you.
The error message gives you the solution right there. Just run
dotenv populate --new
and it will add the missing keys. You can just hit enter on all the options to accept the default.