Ry,
I’m not familiar with mIRC bots, so I can’t help you specifically, but by debugging, I mean figuring out exactly where the code is going wrong. For example, you can add additional “MSG $chan test” lines into your code so that you can see exactly how far it is getting before things stop working.
You can also print out your actual request (uptime in JSONHttpFetch uptime) so that you can look at it and make sure it is correct.