Cannot start observer from IEx shell on MacOS?

iex(8)> :observer.start()

14:26:19.123 [error] ERROR: Could not find '' in: /Users/alex/.asdf/installs/erlang/20.0/lib/wx-1.8.1/priv

 {{:load_driver, 'No driver found'},
    {:wxe_server, :start, 1, [file: 'wxe_server.erl', line: 65]},
    {:wx, :new, 1, [file: 'wx.erl', line: 115]},
    {:observer_wx, :init, 1, [file: 'observer_wx.erl', line: 98]},
    {:wx_object, :init_it, 6, [file: 'wx_object.erl', line: 372]},
    {:proc_lib, :init_p_do_apply, 3, [file: 'proc_lib.erl', line: 247]}

This means you don’t have wxWidgets installed.

I have Erlang installed with `asdf` tool, highly recommended using it for Erlang and Elixir installations.
So if you have Erlang already installed, uninstall it first:

asdf uninstall erlang 20.3

Then you need to install wxWidgets:

brew install wxmac

Check whether you have wxWidgets installed correctly:

wx-config --version

(it should show a version number)

After that you need to install Erlang back:

asdf install erlang 20.3

Voila, you can start observer from your IEx shell: