Never used Nightwatch, but if the tutorial you followed got ‘me’ to write that code, I would back up my horses and approach from a different angle entirely. It’s not wrong code, it’s just incomprehensible to anyone who has not got years of web app testing experience behind them. Soooo welcome to the ministry of test. and thank you for the super brave starting question. I hope you will stay and find your people or tribe here. This is an awesome bunch.
The locator you have on line 17 is pretty much trash, that’s your problem, but training on a public website that is not designed for learning is not a great start. I suggest trying another tutorial , not just for Nightwatch, but for web testing in general. There are loads of them in various threads - example Automation locators - css vs xpath - #3 by testerfromliverpool . Because it’s not just line 17 that is not great, and using an easier to test website for your learning is going to get you more value, and will also teach you how to get rid of those pause (5000) lines, those are the opposite of maintainable test code. Once again welcome and great starter question, hope we can gently guide you along.