Add extensions and export error

Author: MDrakos

graphql.go

@@ -1,33 +1,34 @@
 // Package graphql provides a low level GraphQL client.
 //
-//  // create a client (safe to share across requests)
-//  client := graphql.NewClient("https://machinebox.io/graphql")
+//	// create a client (safe to share across requests)
+//	client := graphql.NewClient("https://machinebox.io/graphql")
 //
-//  // make a request
-//  req := graphql.NewRequest(`
-//      query ($key: String!) {
-//          items (id:$key) {
-//              field1
-//              field2
-//              field3
-//          }
-//      }
-//  `)
+//	// make a request
+//	req := graphql.NewRequest(`
+//	    query ($key: String!) {
+//	        items (id:$key) {
+//	            field1
+//	            field2
+//	            field3
+//	        }
+//	    }
+//	`)
 //
-//  // set any variables
-//  req.Var("key", "value")
+//	// set any variables
+//	req.Var("key", "value")
 //
-//  // run it and capture the response
-//  var respData ResponseStruct
-//  if err := client.Run(ctx, req, &respData); err != nil {
-//      log.Fatal(err)
-//  }
+//	// run it and capture the response
+//	var respData ResponseStruct
+//	if err := client.Run(ctx, req, &respData); err != nil {
+//	    log.Fatal(err)
+//	}
 //
-// Specify client
+// # Specify client
 //
 // To specify your own http.Client, use the WithHTTPClient option:
-//  httpclient := &http.Client{}
-//  client := graphql.NewClient("https://machinebox.io/graphql", graphql.WithHTTPClient(httpclient))
+//
+//	httpclient := &http.Client{}
+//	client := graphql.NewClient("https://machinebox.io/graphql", graphql.WithHTTPClient(httpclient))
 package graphql
 
 import (
@@ -212,7 +213,8 @@ func (c *Client) runWithPostFields(ctx context.Context, req *Request, resp inter
 
 // WithHTTPClient specifies the underlying http.Client to use when
 // making requests.
-//  NewClient(endpoint, WithHTTPClient(specificHTTPClient))
+//
+//	NewClient(endpoint, WithHTTPClient(specificHTTPClient))
 func WithHTTPClient(httpclient *http.Client) ClientOption {
 	return func(client *Client) {
 		client.httpClient = httpclient
@@ -231,17 +233,18 @@ func UseMultipartForm() ClientOption {
 // modify the behaviour of the Client.
 type ClientOption func(*Client)
 
-type graphErr struct {
-	Message string
+type GraphErr struct {
+	Message    string                 `json:"message"`
+	Extensions map[string]interface{} `json:"extensions"`
 }
 
-func (e graphErr) Error() string {
+func (e GraphErr) Error() string {
 	return "graphql: " + e.Message
 }
 
 type graphResponse struct {
 	Data   interface{}
-	Errors []graphErr
+	Errors []GraphErr
 }
 
 // Request is a GraphQL request.