bug257.m:017: In predicate `oops'/2:
bug257.m:017:   warning: unresolved polymorphism.
bug257.m:017:   The variable with an unbound type was:
bug257.m:017:     Gee: V_1
bug257.m:017:   The unbound type variable will be implicitly bound to the
bug257.m:017:   builtin type `void'.
bug257.m:022: Error: the goal inside the require_complete_switch [Gee] scope is
bug257.m:022:   not a switch on `Gee'.
For more information, recompile with `-E'.