Adding additional details to the error message when available (#129)

Author: hiranya911

messaging/messaging.go

@@ -382,6 +382,7 @@ type fcmResponse struct {
 type fcmError struct {
 	Error struct {
 		Status  string `json:"status"`
+		Message string `json:"message"`
 		Details []struct {
 			Type      string `json:"@type"`
 			ErrorCode string `json:"errorCode"`
@@ -439,6 +440,8 @@ func (c *Client) makeSendRequest(ctx context.Context, req *fcmRequest) (string,
 	msg := fcmErrorCodes[code]
 	if msg == "" {
 		msg = fmt.Sprintf("server responded with an unknown error; response: %s", string(resp.Body))
+	} else if fe.Error.Message != "" {
+		msg += "; details: " + fe.Error.Message
 	}
 	return "", fmt.Errorf("http error status: %d; reason: %s", resp.Status, msg)
 }

messaging/messaging_test.go

@@ -627,16 +627,18 @@ func TestSendError(t *testing.T) {
 		},
 		{
 			resp: "{\"error\": {\"status\": \"INVALID_ARGUMENT\", \"message\": \"test error\"}}",
-			want: "http error status: 500; reason: request contains an invalid argument; code: invalid-argument",
+			want: "http error status: 500; reason: request contains an invalid argument; code: invalid-argument; details: test error",
 		},
 		{
 			resp: "{\"error\": {\"status\": \"NOT_FOUND\", \"message\": \"test error\"}}",
-			want: "http error status: 500; reason: app instance has been unregistered; code: registration-token-not-registered",
+			want: "http error status: 500; reason: app instance has been unregistered; code: registration-token-not-registered; " +
+				"details: test error",
 		},
 		{
 			resp: `{"error": {"status": "INVALID_ARGUMENT", "message": "test error", "details": [` +
 				`{"@type": "type.googleapis.com/google.firebase.fcm.v1.FcmErrorCode", "errorCode": "UNREGISTERED"}]}}`,
-			want: "http error status: 500; reason: app instance has been unregistered; code: registration-token-not-registered",
+			want: "http error status: 500; reason: app instance has been unregistered; code: registration-token-not-registered; " +
+				"details: test error",
 		},
 		{
 			resp: "not json",