implement error and healthh endpoints

lib/provider_service_web/controllers/error_json.ex

@@ -0,0 +1,17 @@
+defmodule ProviderServiceWeb.ErrorJSON do
+  @moduledoc """
+  This module is invoked by your endpoint in case of errors on JSON requests.
+  """
+
+  def render("404.json", _assigns) do
+    %{errors: %{detail: "Not Found"}}
+  end
+
+  def render("500.json", _assigns) do
+    %{errors: %{detail: "Internal Server Error"}}
+  end
+
+  def render(template, _assigns) do
+    %{errors: %{detail: Phoenix.Controller.status_message_from_template(template)}}
+  end
+end