createClient.js

const defaultOptions = {
  query: {
    errorPolicy: 'all',
  },
  mutate: {
    errorPolicy: 'all',
  },
}

function createClient(url) {
  const uri = url
  const httpLink = new HttpLink({
    uri,
    fetch: async (uri, options) => {
      // where we inject the headers
      options.headers = await getHeaders()
      return fetch(uri, options)
    },
  })
  
  return new ApolloClient({
    // where we set an InMemoryCache
    cache: new InMemoryCache(),
    link: httpLink,
    defaultOptions
  })
}