[chronojump] Ping WebRequest.Create with try/catch for users with problems on proxy

[Xavier de Blas <xaviblas src gnome org>]

commit df66167efd8b7f2ae78b063a79ecfa5eab2993e0
Author: Xavier de Blas <xaviblas gmail com>
Date:   Wed Jan 30 12:05:41 2019 +0100

    Ping WebRequest.Create with try/catch for users with problems on proxy

 src/json.cs | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)
---
diff --git a/src/json.cs b/src/json.cs
index 9b00a5de..bd797965 100644
--- a/src/json.cs
+++ b/src/json.cs
@@ -219,7 +219,15 @@ public class Json
                requestPingAborting = false;
 
                // Create a request using a URL that can receive a post. 
-               requestPing = WebRequest.Create (serverUrl + "/ping");
+               try {
+                       requestPing = WebRequest.Create (serverUrl + "/ping");
+               } catch {
+                       this.ResultMessage =
+                               string.Format(Catalog.GetString("You are not connected to the Internet\nor 
{0} server is down."),
+                                               serverUrl) + "\n\nMaybe proxy is not configured";
+                       //System.Net.WebRequest.GetSystemWebProxy System.NullReferenceException: Object 
reference not set to an instance of an object
+                       return false;
+               }
 
                // Set the Method property of the request to POST.
                requestPing.Method = "POST";