Quote:its returning my react index.html file
That happens when your server is unable to route the request to the proper router to handle it, and provide a response. If you can debug your server (if you are developing it at the same time!) you will see why the request goes to a fallback handler.
You will have something that handles a wildcard to provide the index.html file as a response.
Quote:I tried using response.json() but got an unexpected token
That is because the JSON files do not start with a "<"; which is the symbol that you find a lot in the HTML documents. Since your server returns an HTML document, it starts with an angle bracket, causing the JSON parser to complain.
Your best bet is to solve the routing problem in your system.