Loop over template "keys" instead of opts keys

installer/templates/phx_ecto/data_case.ex

@@ -45,13 +45,9 @@ defmodule <%= app_module %>.DataCase do
   """
   def errors_on(changeset) do
     Ecto.Changeset.traverse_errors(changeset, fn {message, opts} ->
-      Enum.reduce(opts, message, &replace_message_embed/2)
+      Regex.replace(~r"%{(\w+)}", message, fn _, key ->
+        Map.get(opts, String.to_atom(key), key) |> to_string()
+      end)
     end)
   end
-
-  defp replace_message_embed({_key, value}, message) when is_tuple(value), do: message
-
-  defp replace_message_embed({key, value}, message) do
-    String.replace(message, "%{#{key}}", to_string(value))
-  end
 end