client: Handle NewRequest errors before adding cookies

Previously WriteRequest attempted to add cookies to the httpRequest
instance even if an error happened and might have resulted in
httpRequest being nil which in turn caused a crash.
This patch moves the error handling before looping through the current
cookies to avoid this crash from happening.

Signed-off-by: Vinzenz Feenstra <[email protected]>

Author: vinzenz

client.go

@@ -43,16 +43,16 @@ type clientCodec struct {
 func (codec *clientCodec) WriteRequest(request *rpc.Request, args interface{}) (err error) {
 	httpRequest, err := NewRequest(codec.url.String(), request.ServiceMethod, args)
 
+	if err != nil {
+		return err
+	}
+
 	if codec.cookies != nil {
 		for _, cookie := range codec.cookies.Cookies(codec.url) {
 			httpRequest.AddCookie(cookie)
 		}
 	}
 
-	if err != nil {
-		return err
-	}
-
 	var httpResponse *http.Response
 	httpResponse, err = codec.httpClient.Do(httpRequest)