SyntaxError: Unexpected token < in JSON at position 668 (package.json) [on hold]

I'm pretty new to it, but I'm trying to automate testing in a Shopify webstore with Cypress. The thing is I am unable to do so as, when I try and run the tests, the Cypress browser emulator pops this error before anything:

Error: SyntaxError: Unexpect token < in JSON at position 668 while parsing json file ...\package.json

What makes this error? And any ideas on how to fix it?

Feel free to ask me if more information is needed, just want to fix this issue so I can work on the tests.