How to access PCSC card readers via erlang/elixir?

I am trying to use erlang-pcsc from @arekinath.
But that is my first Erlang program and I blocked on a stupid problem :frowning:

I created a sample code at GitHub - LudovicRousseau/erlang-pcsc-sample: Sample code of PC/SC in Erlang
I use rebar3 escriptize to create a binary.
Then I start it using:

$ ./_build/default/bin/blog 
Hello world!
escript: exception error: undefined function pcsc_card_db:list_readers/0
  in function  escript:run/2 (escript.erl, line 750)
  in call from escript:start/1 (escript.erl, line 277)
  in call from init:start_em/1 
  in call from init:do_boot/3

My code does not find the pcsc functions. I guess it is trivial to fix once you know Erlang a bit more.

My goal is to add an Erlang PC/SC sample to Ludovic Rousseau's blog: PC/SC sample in different languages

I also tried:

$ rebar3 shell
===> Verifying dependencies...
===> Analyzing applications...
===> Compiling blog
Erlang/OTP 24 [erts-12.3.1] [source] [64-bit] [smp:4:4] [ds:4:4:10] [async-threads:1] [jit]

Eshell V12.3.1  (abort with ^G)
1> ===> Booted blog
** exception exit: {noproc,{gen_server,call,[pcsc_card_db,list_readers]}}
     in function  gen_server:call/2 (gen_server.erl, line 239)

Here the function list_readers() is found but I get an exception.

Sorry to ask stupid questions. Can someone help?