Found it.  I needed to NOT use list($id) = pnVarCleanFromInput('id'), 
but rather $id=pnVarCleanFromInput('id').  Very confusing, considering 
other places in the Template module use list($tid, $next) = 
pnVarCleanFromInput('id','next');   Wow.  A function that is stubbornly 
context sensitive, and returns a non-list when it doesn't need to. 

--Alexander