Further revise the Zeitwerk::NameError message

While it could be argued that the previous version
read easily for non-top-level namespaces, let's
have a sentence structure that matches the one for
top-level namespaces.

lib/zeitwerk/loader/callbacks.rb

@@ -18,8 +18,8 @@ module Zeitwerk::Loader::Callbacks
       to_unload[cpath] = [file, cref] if reloading_enabled?
       run_on_load_callbacks(cpath, cget(*cref), file) unless on_load_callbacks.empty?
     else
-      namespace = cref[0] == Object ? "top-level namespace" : "namespace #{real_mod_name(cref[0])}"
-      msg = "expected #{file} to define #{cref[1]} in the #{namespace}"
+      namespace = cref[0] == Object ? "top-level" : real_mod_name(cref[0])
+      msg = "expected #{file} to define #{cref[1]} in the #{namespace} namespace"
       log(msg) if logger
 
       # Ruby still keeps the autoload defined, but we remove it because the

test/lib/zeitwerk/test_exceptions.rb

@@ -29,7 +29,7 @@ def assert_error_message(message, error)
     with_setup(files) do
       typo_rb = File.expand_path("m/typo.rb")
       error = assert_raises(Zeitwerk::NameError) { M::Typo }
-      assert_error_message "expected #{typo_rb} to define Typo in the namespace M", error
+      assert_error_message "expected #{typo_rb} to define Typo in the M namespace", error
       assert_equal :Typo, error.name
     end
   end
@@ -49,7 +49,7 @@ def assert_error_message(message, error)
     with_setup(files) do
       x_rb = File.expand_path("m/x.rb")
       error = assert_raises(Zeitwerk::NameError) { loader.eager_load }
-      assert_error_message "expected #{x_rb} to define X in the namespace M", error
+      assert_error_message "expected #{x_rb} to define X in the M namespace", error
       assert_equal :X, error.name
     end
   end
@@ -64,7 +64,7 @@ def assert_error_message(message, error)
     with_setup(files) do
       cli_x_rb = File.expand_path("cli/x.rb")
       error = assert_raises(Zeitwerk::NameError) { loader.eager_load }
-      assert_error_message "expected #{cli_x_rb} to define X in the namespace Cli", error
+      assert_error_message "expected #{cli_x_rb} to define X in the Cli namespace", error
       assert_equal :X, error.name
     end
   end