DNN Platform v9.2.2

DotNetNuke Google Authentication Project v9.2.2

I've just set up the latest versions (at this time of writing) of DNN and Google Authentication provider via instructions on this page. However, when trying to login via Google, I get "An unexpected error has occurred". When I check the admin logs I see a Page Load Exception.

Pasted below are the exception details:

Message:Value cannot be null. Parameter name: input
StackTrace:
InnerMessage:Value cannot be null. Parameter name: input
InnerStackTrace:

 at 
System.Web.Script.Serialization.JavaScriptSerializer.Deserialize(JavaScriptSerializer
 serializer, String input, Type type, Int32 depthLimit)
   at 
DotNetNuke.Authentication.Google.Components.GoogleClient.GetToken(String
 responseText)
   at 
DotNetNuke.Services.Authentication.OAuth.OAuthClientBase.ExchangeCodeForToken()
   at 
DotNetNuke.Services.Authentication.OAuth.OAuthClientBase.AuthorizeV2()
   at 
DotNetNuke.Services.Authentication.OAuth.OAuthLoginBase.OnLoad(EventArgs
 e)
   at System.Web.UI.Control.LoadRecursive()
   at System.Web.UI.Control.LoadRecursive()
   at System.Web.UI.Control.LoadRecursive()
   at System.Web.UI.Control.LoadRecursive()
   at System.Web.UI.Control.LoadRecursive()
   at System.Web.UI.Control.LoadRecursive()
   at System.Web.UI.Control.LoadRecursive()
   at System.Web.UI.Control.LoadRecursive()
   at System.Web.UI.Control.LoadRecursive()
   at System.Web.UI.Control.LoadRecursive()
   at System.Web.UI.Control.LoadRecursive()
   at System.Web.UI.Control.LoadRecursive()
   at System.Web.UI.Control.LoadRecursive()
   at System.Web.UI.Control.LoadRecursive()
   at System.Web.UI.Page.ProcessRequestMain(Boolean 
includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)

I tried to research this error for days but can't find a resolution. Any advice would be appreciated! Thanks in advance.