Here’s another tip courtesy of the System module.
You know “that” error…?
** (RuntimeError) could not compile application: my_app.
You must restart your server after changing the following files:
config/dev.exs
(phoenix 1.7.12) lib/phoenix/code_reloader/server.ex:236: Phoenix.CodeReloader.Server.mix_compile_unless_stale_config/4
Just do as it says… 
iex> System.restart()
It’ll recompile and reload everything for you.
