Fix various issues reported by Dializer

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

lib/mix/tasks/mobilizon/instance.ex

@@ -130,7 +130,7 @@ defmodule Mix.Tasks.Mobilizon.Instance do
           options,
           :listen_port,
           "What port will the app listen to (leave it if you are using the default setup with nginx)?",
-          4000
+          "4000"
         )
 
       instance_secret = :crypto.strong_rand_bytes(64) |> Base.encode64() |> binary_part(0, 64)

lib/mix/tasks/mobilizon/users/new.ex

@@ -67,10 +67,6 @@ defmodule Mix.Tasks.Mobilizon.Users.New do
       {:error, %Ecto.Changeset{errors: errors}} ->
         shell_error(inspect(errors))
         shell_error("User has not been created because of the above reason.")
-
-      err ->
-        shell_error(inspect(err))
-        shell_error("User has not been created because of an unknown reason.")
     end
   end