Trying to get property of non-object in manage-galleries.php on line 285

Hello, all is updated but still I get the following Notice in the Manage Gallery section (one notice for each single gallery):

Notice: Trying to get property of non-object in …/wp-content/plugins/nextgen-gallery/products/photocrati_nextgen/modules/ngglegacy/admin/manage-galleries.php on line 285

I know notices are not harmful and can be disabled, but still they are recorded in server logs and reduce performances.

How can I solve this issue?

Thank you.