Dictionary widget stopped working after installing Security Update

I'm running High Sierra, and I installed Security Update 2019-005 yesterday. Since then, the Dictionary Dashboard widget has stopped working. The menu that lets you switch between Dictionary and Thesaurus is empty. If I type something into the input field, I get the following log messages in Console:

default	11:40:19.873124 -0400	DashboardClient	CGSConnection: serious error: CID 287495 never existed.
default	11:40:19.873202 -0400	DashboardClient	CGSConnection: current backtrace:: Backtrace (at 0):
default	11:40:19.873249 -0400	DashboardClient	Invalid Connection ID 287495

I can still use the Dictionary application, just not the widget. I tried removing and adding back the widget.