Code is simple:

I'm trying to create a ore that drops item with certain tag, but an error message is sent every time I break the ore:

The game doesn't crash and the tag was set correctly:

But that error message is really annoying.

This should already be fixed in the latest release.
The changes fixing this were committed on Oct 27, 2018

Oh, that's a silly mistake, I'm running on 4.8.0 and the problem was solved after update it to 4.9.1. Thank you.