Am unable to add any Sherlock search plugins recently - haven't checked with builds before and after but bug 599751 seems like the obvious candidate esp. as the error is: _onLoad: Failed to init engine! ReferenceError: valueEnd is not defined Linked url gives example to try.
Ineed, valueEnd is used outside the block where it is declared - let makes that an error.
This bug was caused by not applying some of the whitespace changes :-( To be specific, Serge had outdented the block in question (which was an else after return, so should never have been indented in the first place) which would have meant that let would have worked.
Confirm now works as expected again.
Thanks for catching this, Charles.
Marking as verified fixed then.