After 'mix phx.new generic_rest_server --binary-id --no-install'

lib/generic_rest_server_web/controllers/error_html.ex

@@ -0,0 +1,24 @@
+defmodule GenericRestServerWeb.ErrorHTML do
+  @moduledoc """
+  This module is invoked by your endpoint in case of errors on HTML requests.
+
+  See config/config.exs.
+  """
+  use GenericRestServerWeb, :html
+
+  # If you want to customize your error pages,
+  # uncomment the embed_templates/1 call below
+  # and add pages to the error directory:
+  #
+  #   * lib/generic_rest_server_web/controllers/error_html/404.html.heex
+  #   * lib/generic_rest_server_web/controllers/error_html/500.html.heex
+  #
+  # embed_templates "error_html/*"
+
+  # The default is to render a plain text page based on
+  # the template name. For example, "404.html" becomes
+  # "Not Found".
+  def render(template, _assigns) do
+    Phoenix.Controller.status_message_from_template(template)
+  end
+end