message: Reject subscription operations in httpExchange
diff: @@ -24,7 +24,13 @@ const createAbortController = () => {
  };
  export const httpExchange = (): IExchange => operation => {
  - const { url, fetchOptions } = operation.context;
  + const { url, operationName, fetchOptions } = operation.context;
  +
  + if (operationName === 'subscription') {
  + throw new Error(
  + 'Received a subscription operation in the httpExchange. You are probably trying to create a subscription. Have you added a subscriptionExchange?'
  + );
  + }
  const body = JSON.stringify({
  query: operation.query,
  