errcheck issues fixed (#28556)

server/.golangci.yml

@@ -90,7 +90,6 @@ issues:
         channels/api4/plugin.go|\
         channels/api4/plugin_test.go|\
         channels/api4/post_test.go|\
-        channels/api4/preference_test.go|\
         channels/api4/reaction.go|\
         channels/api4/remote_cluster.go|\
         channels/api4/role.go|\