The location info of a program that belongs to a block is slightly off. Specifically, the loc.start for both the main and inverse are set to the beginning of the block's mustache rather than the end.

Here's a JSBin illustrating it for 3.0.3: http://jsbin.com/yemadanida/1/edit?html,js,console

I also think loc.source should be set to null instead of undefined because it's JSONifyable and it's what's documented anyways.