Invalid argument warning on product pages

Hi WPMU Developers,

We have encountered the following warning:
Warning: Invalid argument supplied for foreach() in /home/meodem1q/public_html/sevenclub/wp-content/plugins/marketpress/includes/common/class-mp-product.php on line 936

After checking it with var_dump(), it seems like the foreach() gets empty strings instead of arrays, so we managed to fix this by casting the variable to array. Like this:

foreach ((array) $this->_variations as $variation) {
			$this->_variation_ids[] = $variation->ID;
}

Ofcourse it isn't the best practice to directly edit the plugin source, so I'm wondering if this can get fixed for the next update.

Thanks in advance!