Unexpected Error

The system encountered an error while processing the following request:
/en_US/default/search/results.displaypanel.displaycell.detailclick/4/ent:$002f$002fSD_ILS$002f1230$002fSD_ILS:1230839/4/4

Error Summary

A component event handler method returned the value Block[Body of search/Results:displaypanel.displaycell.twilightzone, at classpath:com/sirsidynix/discovery/client/components/search/SearchDisplayCell.tml, line 195]. Return type org.apache.tapestry5.internal.structure.BlockImpl can not be handled.
Thu Jun 20 14:32:46 EEST 2019