Add the failed module to the exception message.

This way it makes clearer what module we are referring to.

Author: Ricardo de Cillo

lib/iex/lib/iex/helpers.ex

@@ -309,7 +309,7 @@ defmodule IEx.Helpers do
 
   defp do_r(module) do
     unless Code.ensure_loaded?(module) do
-      raise ArgumentError, message: "The module is not loaded and it could not be found"
+      raise ArgumentError, message: "could not load nor find module: #{inspect module}"
     end
 
     source = source(module)

lib/iex/test/iex/helpers_test.exs

@@ -305,7 +305,7 @@ defmodule IEx.HelpersTest do
   end
 
   test "r helper unavailable" do
-    assert_raise ArgumentError, "The module is not loaded and it could not be found", fn ->
+    assert_raise ArgumentError, "could not load nor find module: :non_existent_module", fn ->
       r :non_existent_module
     end
   end