"Argument Error" in simple module

I have a simple, stand alone module that yields:

elixir impl_bad.ex
** (ArgumentError) argument error

In iex:
=> iex
Erlang/OTP 23 [erts-11.1] [source] [64-bit] [smp:12:12] [ds:12:12:10] [async-threads:1] [hipe]

Interactive Elixir (1.9.4) - press Ctrl+C to exit (type h() ENTER for help)
iex(1)> c “impl_bad.ex”

== Compilation error in file impl_bad.ex ==
** (ArgumentError) argument error

** (ArgumentError) argument error

The code:

defmodule ImplBad do
def run_addition_problems(aconfig) do

Place this 5 line code in a file by itself.

I know do_addition_problems() does not
exist but I would expect and undefined error.

I extracted this code from a project file where
do_addition_problems() does exists.

Is this a problem with elixir 1.9.4?

Perhaps, I get this error on Elixir 1.10.0

** (CompileError) foo.ex:3: undefined function do_addition_problems/1
    (elixir 1.10.0) src/elixir_locals.erl:114: anonymous fn/3 in :elixir_locals.ensure_no_undefined_local/3
    (stdlib 3.13.2) erl_eval.erl:680: :erl_eval.do_apply/6