I managed to figure out a solution. It turns out that when using PHP5.4, the empty() function can only take variables, whereas in PHP5.5 this line would have worked.

As a note, if anyone else encounters this issue and doesn't want to update their PHP version, a simple fix is to rewrite it as such:

$korinscustom1 = getParam('sys_embedly_api_key');
$korinscustom2 = getParam('sys_embedly_api_patter');
$bEmbedly = !empty($korinscustom1) && !empty($korinscustom2);

It also might be worth updating the installation documentation to state that PHP5.5 must be used. I tried it initially with PHP5.6, but there were modules missing which I could not find a way to install myself.