Why does next not give an error if no next method is available?

oo::class create A  {method a {} {puts actionA}}
oo::class create AM {
	method a {} {puts actionAM ; next}
}
oo::define A mixin AM
A create a
% a a
ActionA
% a b
mmh
%
# where did actionAM go? Mixins should be called before the instance methods. If this would be the case. Silently nooping next would not be need