sudo --preserve-env mix gatling.deploy returns no function clause matching IO.chardata_to_string/1

[Preen]

When I run MIX_ENV=prod sudo --preserve-env mix gatling.deploy my_app I get this error:

** (FunctionClauseError) no function clause matching in IO.chardata_to_string/1

The following arguments were given to IO.chardata_to_string/1:

    # 1
    nil

(elixir) lib/io.ex:445: IO.chardata_to_string/1
(elixir) lib/path.ex:500: Path.do_join/3
(elixir) lib/path.ex:495: Path.join/2
(elixir) lib/path.ex:472: Path.join/1
lib/gatling/gatling.ex:19: Gatling.env/2
lib/gatling/tasks/deploy.ex:28: Mix.Tasks.Gatling.Deploy.deploy/1
(mix) lib/mix/task.ex:301: Mix.Task.run_task/3
(mix) lib/mix/cli.ex:75: Mix.CLI.run_task/2

I have a elixir cluster project with one phoenix app inside it. This is on Ubuntu 16.04 LTS. I can compile the project in production mode on local computer.

[tgautier]

Same issue here, I've found that gatling was looking for :version and :app in your mix.exs project function.

After having added those, I now run into the following cryptic error:

warning: redefining module MyApp.Mixfile (current version defined in memory)
  nofile:1

** (Mix) Trying to load MyApp.Mixfile from "nofile" but another project with the same name was already defined at "nofile"

It looks like this project is no longer active.

[ConnorRigby]

I have this issue also. Any resolution?