Loading Data... Wanikani user

Looks like you never got an answer to this. Network is the 4th tab in the devtools (step 1 in image)
After you open it, hit Ctrl+R to reload the page and capture all the network traffic. (step 2 in image)

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There will be a long list, but once it stops loading more, hit the red “record” button in the top left of the tab to stop the recording and look at the results (step 3 in image). From your error, it looks like the user call doesn’t get a response.

Once you find the request, the mini section on the right has tabs to look at HTTP headers, the received response, etc. This information could help to narrow down the problem. Your console indicates the JSON response is terminated unexpectedly - usually this means no response at all (or a 404 return status or something), but it can have different causes.