Update src/Microsoft.Owin.Security.Authorization.Mvc/ResourceAuthorizeAttribute.cs

Co-Authored-By: David Parks <[email protected]>

Author: lavignep007

src/Microsoft.Owin.Security.Authorization.Mvc/ResourceAuthorizeAttribute.cs

@@ -46,7 +46,7 @@ protected override bool AuthorizeCore(HttpContextBase httpContext)
             }
 
             var filterContext = httpContext.Items[s_authorizationContextKey] as System.Web.Mvc.AuthorizationContext;
-            var controller = filterContext.Controller as IAuthorizationController;
+            var controller = filterContext?.Controller as IAuthorizationController;
             var user = (ClaimsPrincipal)httpContext.User;
             var contextAccessor = new HttpContextBaseOwinContextAccessor(httpContext);
             var authorizationHelper = new AuthorizationHelper(contextAccessor);