During CLi Installation of Moodle 3.1.5 following error occurs:

++ Unsupported $module syntax detected in version.php of the mod_hotpot plugin. ++ * line 322 of /lib/classes/plugin_manager.php: call to debugging() * line 348 of /lib/classes/plugin_manager.php: call to core_plugin_manager->load_present_plugins() * line 217 of /lib/classes/plugininfo/base.php: call to core_plugin_manager->get_present_plugins() * line 143 of /lib/classes/plugininfo/base.php: call to core\plugininfo\base->load_disk_version() * line 97 of /lib/classes/plugininfo/base.php: call to core\plugininfo\base::make_plugin_instance() * line 408 of /lib/classes/plugin_manager.php: call to core\plugininfo\base::get_plugins() * line 43 of /admin/settings/plugins.php: call to core_plugin_manager->get_plugins_of_type() * line 7279 of /lib/adminlib.php: call to require() * line 7300 of /lib/adminlib.php: call to admin_get_root() * line 1635 of /lib/upgradelib.php: call to admin_apply_default_settings() * line 481 of /lib/installlib.php: call to install_core() * line 184 of /admin/cli/install_database.php: call to install_cli_database()

After that message the installation process continues and finish successful.