I think you missed the back quotes in the command, essentially passing the ip directly, with empty result (but not an error, which is what the script is looking for).
still I can’t see it making a difference to my current state of puzzlement over this one, it remains a bit of a mystery (for the time being).
I did modify the script further though, to avoid passing multiple IPs (or in your case a duplicate of a single one), so if you’d like you could try running the script again without bypassing the check and see if you still run into the issue:
curl -sS https://raw.githubusercontent.com/pimoroni/get/master/installers/envirophat | bash
(same url as before, but no argument passed)
… I’m not convinced it will make a difference, but perhaps I got lucky guessing what might be the possible cause for the failure ;-)