Maximum nesting level reached with Radium One Click Demo Install

Overview of the issue

Radium One Click Demo Install is a library for importing demo content to WordPress sites.

It is included in a variety of themes and causes the following infinite loop when used together with WPML:

PHP Fatal error:  Maximum function nesting level of '100' reached, aborting!

Workaround

The suggested workaround is available on the library’s GitHub page:

https://github.com/FrankM1/radium-one-click-demo-install/issues/33

All you have to do is to edit the file inc/theme-options/importer/importer/radium-importer.php in your theme and wrap the add_filter() with an if statement:

        global $pagenow;
        if ( $pagenow === 'themes.php' ) {
            add_filter( 'add_post_metadata', array( $this, 'check_previous_meta' ), 10, 5 );
        }

Please note that the actual location of the file may vary from theme to theme and the themes that include this library would need to be updated too.