Fatal error – cannot activate

Updated WP Staging to version 2.4.4 earlier today. The plugin was already activated at that time. After updating, experienced problems with editing posts/pages. Could not switch from visual editor to text view, and could not insert or update links in visual editor. Editing problems went away when WP Staging was deactivated. Now when trying to activate WP Staging again, activation fails with this error message: “Plugin could not be activated because it triggered a fatal error. Fatal error: Using $this when not in object context in [file_path]/plugins/wp-staging/install.php on line 29.”

Site is not yet updated to WordPress 5.0 pending testing.