Asset Shredder not working in RT 3.8.1

I’ve been able to get Asset Tracker working fairly well in RT 3.8.1, but
Asset Shredder returns the following error when trying to wipeout assets:
Can’t locate object method “SetResolvers” via package
"RT::Shredder::Plugin::Assets" at
/opt/rt3/share/html/Admin/Tools/Shredder/index.html line 152.

I’m not sure where to begin with this, and would appreciate any suggestions.