fix type of returned args for 0 arity #401

Job	Run time
static analysis (Elixir 1.15.x \| Erlang/OTP 26.x)	1m 5s
mix test (Elixir 1.13.x \| Erlang/OTP 22.x)	1m 2s
mix test windows (Elixir 1.13.x \| Erlang/OTP 22.x)	2m 24s
mix test (Elixir 1.13.x \| Erlang/OTP 23.x)	1m 1s
mix test (Elixir 1.13.x \| Erlang/OTP 24.x)	1m 13s
mix test windows (Elixir 1.13.x \| Erlang/OTP 23.x)	2m 16s
mix test (Elixir 1.13.x \| Erlang/OTP 25.x)	1m 6s
mix test windows (Elixir 1.13.x \| Erlang/OTP 24.x)	2m 20s
mix test (Elixir 1.14.x \| Erlang/OTP 23.x)	1m 3s
mix test windows (Elixir 1.13.x \| Erlang/OTP 25.x)	2m 41s
mix test (Elixir 1.14.x \| Erlang/OTP 24.x)	53s
mix test windows (Elixir 1.14.x \| Erlang/OTP 23.x)	2m 29s
mix test (Elixir 1.14.x \| Erlang/OTP 25.x)	1m 3s
mix test windows (Elixir 1.14.x \| Erlang/OTP 24.x)	3m 16s
mix test (Elixir 1.14.x \| Erlang/OTP 26.x)	54s
mix test windows (Elixir 1.14.x \| Erlang/OTP 25.x)	2m 9s
mix test (Elixir 1.15.x \| Erlang/OTP 24.x)	1m 1s
mix test windows (Elixir 1.14.x \| Erlang/OTP 26.x)	2m 15s
mix test (Elixir 1.15.x \| Erlang/OTP 25.x)	58s
mix test windows (Elixir 1.15.x \| Erlang/OTP 24.x)	2m 55s
mix test (Elixir 1.15.x \| Erlang/OTP 26.x)	1m 1s
mix test windows (Elixir 1.15.x \| Erlang/OTP 25.x)	1m 55s
mix test windows (Elixir 1.15.x \| Erlang/OTP 26.x)	1m 51s
	38m 51s

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