Hide system actor from user list and block show/edit

Index: filter out SystemActor.system_user_email() in query. Show/Form:
redirect to /users with flash when viewing or editing system actor user.
Index format_error: handle Ash errors without :message field.

lib/mv_web/live/user_live/show.ex

@@ -75,9 +75,16 @@ defmodule MvWeb.UserLive.Show do
     actor = current_actor(socket)
     user = Ash.get!(Mv.Accounts.User, id, domain: Mv.Accounts, load: [:member], actor: actor)
 
-    {:ok,
-     socket
-     |> assign(:page_title, gettext("Show User"))
-     |> assign(:user, user)}
+    if to_string(user.email) == Mv.Helpers.SystemActor.system_user_email() do
+      {:ok,
+       socket
+       |> put_flash(:error, gettext("This user cannot be viewed."))
+       |> push_navigate(to: ~p"/users")}
+    else
+      {:ok,
+       socket
+       |> assign(:page_title, gettext("Show User"))
+       |> assign(:user, user)}
+    end
   end
 end