Why does the created checkStatus function return a Promise: fulfilled but with an undefined value?

So, I created the code below just like Guil did in the video, and I got an error,

"Uncaught (in promise) TypeError: Cannot read property 'message' of undefined"

Troubleshooting this, I found that commenting out .then(checkStatus) fixed the error. So I added,

console.log(Promise.resolve);

to the checkStatus function. When I ran it again, I got the same error, and console logged:

Promise {<fulfilled>: undefined} proto: Promise [[PromiseStatus]]: "fulfilled" [[PromiseValue]]: undefined

So I figured out that what's breaking the code is that checkStatus is returning the undefined Promise. My question is why? Is there a way around this? I noticed in the video Guil's console logs a similar error. Is it a problem with the code itself?

Thanks in advance!

Code snippet: function fetchData(url){ return fetch(url) .then(checkStatus)
.then(res => res.json()) .catch(error => console.log('Looks like there was a problem', error)) }

function checkStatus (response) { if(response.ok) { console.log(Promise.resolve()); return Promise.resolve(); } else { return Promise.reject(new Error(response.statusText)) } }