Hi, it's me again, I'm soo close to getting this working now.

I would have assumed that this was my fault somehow if it wasn't for the fact that this error is mentioned in your documentation. Albeit in a completely different file. Now I'm getting this error in one of the stock (vendor) templates, not in something I modified myself.
Now, I have barely started to learn the inner workings of Sylius so I may be completely off target here, but the documentation mentions that you inject something globally. Could your "remote_url" be conflicting with some other "remote_url"?
These are the relevant packages in my composer.json:
"require": {
"php": "^7.2",
"loevgaard/sylius-brand-plugin": "^2.0",
"sylius/shop-api-plugin": "^1.0@RC",
"sylius/sylius": "~1.5.0",