!empty($_GET[])
Well there are various ways to fix your error, but I require a context in No, it's never a good tip, as much as enabling notices and warnings in...
That's not an error.
Also you can just: if (@getimagesize($x->image_url)) { echo "img"; }
if (filter_var($url, FILTER_VALIDATE_URL)) { /* then set the variable */ }
Can you show how $x->image_url is being set?
Separate names with a comma.