phrase/2 too eager execution

[UWN]

| ?- phrase(([a],{1}),[]).

no, unexpected.
   type_error(callable,...). % expected, but not found

The idea is that the logical grammar rule expansion happens without any error conditions satisfied, and then the expanded term is called.

[UWN]

Also note that minor modifications make the error appear as expected (#37):

| ?- phrase((!,[a],{1}),[]).
uncaught exception: error(type_error(callable,(!,[]=[a|_292],1,_292=[])),phrase/2)