Default Object error after upgrading to PHP 5.5

Now my site is throwing a default object from empty value error and I don’t have any idea why this happens…

According to the error report this is the line of code which causes the issue

<a href="'. get_permalink($post-> ID = $id ) .'" title="'. get_the_title( $post->ID=$id ).'" >' ;

would be great if someone could help me with this…

Thanks