Response Isn't Converting To JSON - ruby-on-rails

Question

I'm trying to take info from a React form and post it to my Rails database, but I get an error "unexpected token '<' at position 0" which means my response is still HTML and not JSON.
Here's my code:
export const createCar = car => {
return dispatch => {
return fetch(`${API_URL}/cars/create`, {
method: "POST",
headers: {
'Content-type': 'application/json'
},
body: JSON.stringify({ car: car })
})
.then(response => response.json())
.then(car => {
dispatch(addCar(car))
dispatch(resetCarForm())
})
.catch(error => console.log(error + 'createCar POST failed'))
}
}
Is there a reason why it's not converting to JSON?
Additionally, I don't seem to be able to drop debugger into my code, or at least in this function - do I need to import it or something?

Answer 1

I'm thinking that your server is sending you back HTML and then you are trying to parse it in response.json()
use a try/catch in this block:
export const createCar = car => {
return dispatch => {
return fetch(`${API_URL}/cars/create`, {
method: "POST",
headers: {
'Content-type': 'application/json'
},
body: JSON.stringify({ car: car })
})
.then(response => {
try {
return response.json()
} catch(error) {
console.error(error);
}
})
.then(car => {
dispatch(addCar(car))
dispatch(resetCarForm())
})
.catch(error => console.log(error + 'createCar POST failed'))
}