@exetico @Curtis_Kephart After some digging it turns out that the issue you both reported will not occur if you run Discourse on any commit after (and including) this one
If you’re running Discourse on an older commit you’ll get this error
Unexpected error while indexing post for search : PG::NotNullViolation: ERROR: null value in column “private_message” violates not-null constraint
The plugin (unchanged) works as expected on the latest version of Discourse.