Unexpected Error

The system encountered an error while processing the following request:
/en_US/default/search/mylists.listdetails.displaycell.detailclick/ent:$002f$002fERC_8989_1779$002f0$002fTHREE_M:esw3x89/1/1/0

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.
Sat Oct 20 15:32:13 CDT 2018