Why am I getting this error? Expected to find settings under `config nil, Ueberauth.Strategy.Auth0.OAuth`, got nil. Check your config.exs

Question

I was following this tutorial https://auth0.com/blog/elixir-and-phoenix-tutorial-build-an-authenticated-app/#Our-Phoenix-application-skeleton and everything was working fine until I tried to run it with the auth enabled. Now I keep getting this error:

** (RuntimeError) Expected to find settings under `config nil, Ueberauth.Strategy.Auth0.OAuth`, got nil. Check your config.exs.

Here is my config.exs...

  1 # and its dependencies with the aid of the Mix.Config module.
  2 #
  3 # This configuration file is loaded before any dependency and
  4 # is restricted to this project.
  5
  6 # General application configuration
  7 use Mix.Config
  8
  9 config :countdown,
 10   ecto_repos: [Countdown.Repo]
 11
 12 # Configures the endpoint
 13 config :countdown, CountdownWeb.Endpoint,
 14   url: [host: "localhost"],
 15   secret_key_base: "bur+iF3WjRBI22r3j/Yzh4O3//lVXhSnpyVZKFjBllvBKv5Neyh1zQKsLDLZuB9K",
 16   render_errors: [view: CountdownWeb.ErrorView, accepts: ~w(html json), layout: false],
 17   pubsub_server: Countdown.PubSub,
 18   live_view: [signing_salt: "waO+DlgX"]
 19
 20 # Configures Elixir's Logger
 21 config :logger, :console,
 22   format: "$time $metadata[$level] $message\n",
 23   metadata: [:request_id]
 24
 25 # Use Jason for JSON parsing in Phoenix
 26 config :phoenix, :json_library, Jason
 27
 28 # Configures Ueberauth
 29 config :ueberauth, Ueberauth,
 30   providers: [
 31     auth0: {Ueberauth.Strategy.Auth0, []},
 32   ]
 33
 34 # Import environment specific config. This must remain at the bottom
 35 # of this file so it overrides the configuration defined above.
 36 import_config "#{Mix.env()}.exs"

I also have...

+# Configures Ueberauth's Auth0 auth provider
+config :ueberauth, Ueberauth.Strategy.Auth0.OAuth,
+  domain: System.get_env("AUTH0_DOMAIN"),
+  client_id: System.get_env("AUTH0_CLIENT_ID"),
+  client_secret: System.get_env("AUTH0_CLIENT_SECRET")

in my config/dev.exs file.

I realize that this tutorial is very old but I couldn't find anything more recent. I looked at the Ueberauth_auth0 docs and they mention that you need to start ueberauth_auth0 before you start your application. I'm pretty new to Elixir/Phoenix and I'm not sure if that could be the issue or how to solve it? That seems to be the only thing that I am missing based on the tutorial, docs, and Ueberauth example app.

Any ideas?