how could the user have JSON::Any but no valid decoder?

e.g.
http://www.cpantesters.org/cpan/report/03004ad4-8811-11e3-96be-b355934679b0
http://www.cpantesters.org/cpan/report/56f2724e-8734-11e3-93bb-dbb3924679b0
http://www.cpantesters.org/cpan/report/c385c7ba-8655-11e3-8996-c560934679b0
Dist-Zilla-Plugin-OptionalFeature-0.012

          - report more installed versions, as an attempt to debug some odd
            cpantesters failures