Perhaps the issue is that `lookupProperty` returns undefined for the layoutTemplate and that causes problems here: https://github.com/EventedMind/blaze-layout/blob/master/layout.js#L132. Because if the value is undefined, it thinks you're using the method as a getter instead of a setter.

So we'll need to verify this is the issue. If it is, we can either coerce undefined to null or false from IronRouter, or probably better, just make a more explicit API in blaze-layout like getTemplate, setTemplate. That way undefined, false, and null make it through as possible values.