improvement: provide better error message on hijack protection

lib/mix/tasks/ash_authentication_phoenix.install.ex

@@ -271,7 +271,21 @@ defmodule Mix.Tasks.AshAuthenticationPhoenix.Install do
         |> redirect(to: return_to)
       end
 
-      def failure(conn, _activity, _reason) do
+      def failure(conn, activity, reason) do
+        message =
+          case {activity, reason} do
+            {{:magic_link, _},
+            %AshAuthentication.Errors.AuthenticationFailed{
+              caused_by: %Ash.Error.Forbidden{
+                errors: [%AshAuthentication.Errors.CannotConfirmUnconfirmedUser{}]
+              }
+            }} ->
+              "You have already signed in another way, but have not confirmed your account. Please confirm your account."
+
+            _ ->
+              "Incorrect email or password"
+          end
+
         conn
         |> put_flash(:error, "Incorrect email or password")
         |> redirect(to: ~p"/sign-in")