Unexpected Error

The system encountered an error while processing the following request:
/en_US/default/search/mylists.listdetails.displaycell.detailclick/ent:$002f$002fSD_ILS$002f0$002fSD_ILS:178583/20/20/0

Error Summary

A component event handler method returned the value Block[Body of search/MyLists:listdetails.displaycell.twilightzone, at classpath:com/sirsidynix/discovery/client/components/search/SearchDisplayCell.tml, line 215]. Return type org.apache.tapestry5.internal.structure.BlockImpl can not be handled.
Tue Apr 24 09:32:06 CDT 2018