I'm following their official tutorial and the query tutorial works perfectly but the mutation throws the error in the title when I press the button in the following code. https://www.apollographql.com/docs/react/data/mutations/

const ADD_USER = gql` mutation AddUser($name: String!) { addUser(name: $name) { name } } `;

const [addUser, {data}] = useMutation(ADD_USER);