I receive this message when I make a post request. I'm posting data from json list and posting it into a new list. The initial post works, the 2nd time I click on the data I receive this error:

"POST http://localhost:3000/wishlist 500 (Internal Server Error)" "Uncaught (in promise) SyntaxError: Unexpected token E in JSON at position 0" "Error: Insert failed, duplicate id"

I believe it has to do with making a 2nd post request on the same ID, but I don't know how to fix it.

Below is the code:

const postStadiumToWishList = (stadium) => {
    fetch(baseUrl + '/wishlist' , {
        method: "POST", 
        headers: {
            'Accept': 'application/json', 
            'Content-Type': 'application/json' 
        },
        body: JSON.stringify(stadium)
    })
    .then(resp => resp.json())
    .then(data => {
        stadiums.push(data)
    })
}