Welcome!
Looking at this example, I am unsure why the given Error message is displayed, but one thing to correct would be that you are passing the explicit string process.env.T_CHANNEL instead of the value of said environment variable.
You’ll want to remove the ’ around it and you may then get somewhere.
Additionally, I recommend checking out TMI.js’ Documentation and Discord - it’s a community-driven library and not made by Twitch.
If you wanted, you could look at connecting to Twitch’s IRC interface yourself via WebSockets - you can find more information in the docs.