Fix scopes may be null bug.

modules/account/src/Volo.Abp.Account.Web.IdentityServer/Pages/Consent.cshtml.cs

@@ -187,7 +187,9 @@ namespace Volo.Abp.Account.Web.Pages
 
             public List<string> GetAllowedScopeNames()
             {
-                return IdentityScopes.Union(ApiScopes).Where(s => s.Checked).Select(s => s.Name).ToList();
+                var identityScopes = IdentityScopes ?? new List<ConsentModel.ScopeViewModel>();
+                var apiScopes = IdentityScopes ?? new List<ConsentModel.ScopeViewModel>();
+                return identityScopes.Union(apiScopes).Where(s => s.Checked).Select(s => s.Name).ToList();
             }
         }