fix file uploads, serve them properly, put behind auth wall, decrypt secret message in frontend

lib/entendu_web/views/error_view.ex

@@ -13,4 +13,13 @@ defmodule EntenduWeb.ErrorView do
   def template_not_found(template, _assigns) do
     Phoenix.Controller.status_message_from_template(template)
   end
+
+  def render("error_code.json", %{message: message} = params) do
+    code = Map.get(params, :code, "")
+
+    %{
+      message: message,
+      code: code
+    }
+  end
 end