Closed Issue: System.NullReferenceException: Object reference not set to an instance of an object. [26752]

From time to time, my clients gets this error.

System.NullReferenceException: Object reference not set to an instance of an object.
at System.Collections.Generic.Dictionary`2.Insert(TKey key, TValue value, Boolean add)
at AjaxControlToolkit.ToolkitScriptManager.GetScriptCombineAttributes(Assembly assembly)
at AjaxControlToolkit.ToolkitScriptManager.IsScriptCombinable(ScriptEntry scriptEntry)
at AjaxControlToolkit.ToolkitScriptManager.OnResolveScriptReference(ScriptReferenceEventArgs e)
at System.Web.UI.ScriptManager.RegisterScripts()
at System.Web.UI.ScriptManager.OnPagePreRenderComplete(Object sender, EventArgs e)
at System.Web.UI.Page.OnPreRenderComplete(EventArgs e)
at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
Comments: Fixed with January 2013 Release of the Ajax Control Toolkit -- Pull Request merged.