error.ex

$ mix ryal.install
==> ryal_core
Compiling 1 file (.ex)
** (UndefinedFunctionError) function App.Repo.config/0 is undefined (module App.Repo is not available)
    App.Repo.config()
    lib/mix/ecto.ex:162: Mix.Ecto.build_repo_priv/1
    lib/mix/ecto.ex:148: Mix.Ecto.migrations_path/1
    lib/mix/tasks/ryal.core.install.ex:46: Mix.Tasks.Ryal.Core.Install.project_migration_dir/0
    lib/mix/tasks/ryal.core.install.ex:9: Mix.Tasks.Ryal.Core.Install.run/1
    (mix) lib/mix/task.ex:294: Mix.Task.run_task/3
    (mix) lib/mix/cli.ex:58: Mix.CLI.run_task/2
    (elixir) lib/code.ex:370: Code.require_file/2

ryal.core.install.ex

# Location on Github:
#
#   https://github.com/ryal/ryal/blob/master/apps/ryal_core/lib/mix/tasks/ryal.core.install.ex
#
defmodule Mix.Tasks.Ryal.Core.Install do
  @moduledoc "Installs all Ryal Core migrations."

  use Mix.Task

  alias Mix.Ecto

  def run(_) do
    File.mkdir_p project_migration_dir()
    stamp = String.to_integer timestamp()

    ryal_core_migrations()
    |> Stream.with_index
    |> Enum.each(fn({ryal_core_migration, index}) ->
      migration = "#{stamp + index}_#{migration_name(ryal_core_migration)}"
      copy_migration(ryal_core_migration, migration)
    end)
  end

  # ...

  defp project_migration_dir do
    dir = Ecto.migrations_path Ryal.repo() # <-- the offending line of code
    marketplace? = Application.get_env(:ryal_core, :marketplace)
    if marketplace?, do: marketplace_migrations_folder(dir), else: dir
  end

  # ...
end

ryal.ex

# Location on Github:
#
#   https://github.com/ryal/ryal/blob/master/apps/ryal_core/lib/ryal.ex
#
defmodule Ryal do
  @repo Application.get_env(:ryal_core, :repo)

  def repo, do: @repo
end