This seems broken to me .... I think?

> public function get($key, $type=null)

This function will get the data by key, whatever the type is, if you pass null for $type. All great!

> public function remove($key, $type=null) {

If you pass null for $type, this will fail to remove the object!

Worse, it will report the removal as a success by returning true! (I assume that's the point of the "return true"?)

The culprit seems to be this line in the remove function.

> if ($node->key === $key && $node->type == $type) {

This forcibly checks the type, even if you passed null! Shouldn't it be something like:

> if ($node->key === $key && (is_null($type) || $node->type == $type)) {