Specifically, this happens when a resource is lazy-loading a property
that includes DirtyMinder: Resource#eager_load iterates over the set of
properties to lazy-load and calls Property#set with nil for each before
calling Collection#lazy_load. The Property#set call blows up when given
nil because DirtyMinder tries to add instance variables to nil—@resource
& @Property in DirtyMinder#wrap_value—which is a frozen object and thus
blows up.   Do the research if you don't believe me. Seriously, please
do; I'd love to be proven wrong about this. Anyways, nil can't be
mutated, thus I don't think anyone cares about tracking nil, so this
fix/work-around should not impact functionality at all.

My changes were based on a ref that had a Wrapper module, now it's called Hooker.

But I won't.

Also outdent the private keyword, because outdented method visibility declarations are the bees knees.