Fix error not printed to console when no name is provided

When minetest is launched, if there was no nameprovided in
configuration or parameters, the game would not show any error in
console. if the --go parameter was also prowided, the game would
exit without an error. This is undesired behavior, so this merged
commit add the missing function that displays the missing error
message in console.

src/client/clientlauncher.cpp

@@ -401,6 +401,7 @@ bool ClientLauncher::launch_game(std::string &error_message,
 
 	if (menudata.name == "" && !simple_singleplayer_mode) {
 		error_message = gettext("Please choose a name!");
+		errorstream << error_message << std::endl;
 		return false;
 	}