67:1 Uncaught (in promise) SyntaxError: Unexpected token '<', "<!DOCTYPE "... is not valid JSON P

I'm doing a tutorial from scrimba for react and react router 6 and I'm encountering an error with the provided data. The error says 67:1 Uncaught (in promise) SyntaxError: Unexpected token '<', "<!DOCTYPE "... is not valid JSON
P and is at line 9 which is .then(data => setVans(data.vans)). The whole code for Vans.jsx is:

import React from 'react'
import { Link } from 'react-router-dom'

export default function Vans() {
    const [vans, setVans] = React.useState([])
    React.useEffect(() => {
        fetch("/api/vans")
            .then(res => res.json())
            .then(data => setVans(data.vans))
    }, [])

    const vanElements = vans.map(van => (
        <div key={van.id} className="van-tile">
            <Link to={`/vans/${van.id}`}>
                <img src={van.imageUrl} />
                <div className="van-info">
                    <h3>{van.name}</h3>
                    <p>${van.price}<span>/day</span></p>
                </div>
                <i className={`van-type ${van.type} selected`}>{van.type}</i>
            </Link>
        </div>
    ))

    return (
        <div className="van-list-container">
            <h1>Explore our van options</h1>
            <div className="van-list">
                {vanElements}
            </div>
        </div>
    )
}

The data from the api is coming from server.js which is:

import { createServer, Model } from "miragejs"


createServer({
    models: {
        vans: Model,
    },

    seeds(server) {
        server.create("van", { id: "1", name: "Modest Explorer", price: 60, description: "The Modest Explorer is a van designed to get you out of the house and into nature. This beauty is equipped with solar panels, a composting toilet, a water tank and kitchenette. The idea is that you can pack up your home and escape for a weekend or even longer!", imageUrl: "https://assets.scrimba.com/advanced-react/react-router/modest-explorer.png", type: "simple" })
        server.create("van", { id: "2", name: "Beach Bum", price: 80, description: "Beach Bum is a van inspired by surfers and travelers. It was created to be a portable home away from home, but with some cool features in it you won't find in an ordinary camper.", imageUrl: "https://assets.scrimba.com/advanced-react/react-router/beach-bum.png", type: "rugged" })
        server.create("van", { id: "3", name: "Reliable Red", price: 100, description: "Reliable Red is a van that was made for travelling. The inside is comfortable and cozy, with plenty of space to stretch out in. There's a small kitchen, so you can cook if you need to. You'll feel like home as soon as you step out of it.", imageUrl: "https://assets.scrimba.com/advanced-react/react-router/reliable-red.png", type: "luxury" })
        server.create("van", { id: "4", name: "Dreamfinder", price: 65, description: "Dreamfinder is the perfect van to travel in and experience. With a ceiling height of 2.1m, you can stand up in this van and there is great head room. The floor is a beautiful glass-reinforced plastic (GRP) which is easy to clean and very hard wearing. A large rear window and large side windows make it really light inside and keep it well ventilated.", imageUrl: "https://assets.scrimba.com/advanced-react/react-router/dreamfinder.png", type: "simple" })
        server.create("van", { id: "5", name: "The Cruiser", price: 120, description: "The Cruiser is a van for those who love to travel in comfort and luxury. With its many windows, spacious interior and ample storage space, the Cruiser offers a beautiful view wherever you go.", imageUrl: "https://assets.scrimba.com/advanced-react/react-router/the-cruiser.png", type: "luxury" })
        server.create("van", { id: "6", name: "Green Wonder", price: 70, description: "With this van, you can take your travel life to the next level. The Green Wonder is a sustainable vehicle that's perfect for people who are looking for a stylish, eco-friendly mode of transport that can go anywhere.", imageUrl: "https://assets.scrimba.com/advanced-react/react-router/green-wonder.png", type: "rugged" })
    },

    routes() {
        this.namespace = "api"

        this.get("/vans", (schema, request) => {
            return schema.vans.all()
        })
        
        this.get("/vans/:id", (schema, request) => {
            const id = request.params.id
            return schema.vans.find(id)
        })
    }
})

I've copied and pasted the code from the tutorial but is still getting the error. Anyone know what I'm missing here?

You're running this on your local right? I had the same issue. The problem was an import in the index.jsx file.

On Scrimba, they have import "./server"
I had to simply add a dot import "../server" because the local react build put the index.jsx file in the src folder.