If you are on nodebb 1.12.2 you should use the version of db search in your package.json. 4.0.6 is for nodebb 1.13.0 which isn't released yet.
Active users broken
There seems to be a problem with the Active Users widget. It shows up fine in the forum, but when any user is clicked on, the error happens for this route:
Fixed in widget-essentials 1.0.3. Thanks for reporting.
Thanks again, Baris. Testing now.