Active conduits deal damage to (non-trap) skeleton horses, despite them not being hostile mobs. Conduits are only supposed to damage hostile mobs.

Steps to reproduce:

1. Build a conduit frame (with at least 42 prismarine blocks so that the conduit attacks mobs) and activate a conduit.
2. Move a non-trap skeleton horse within 8 blocks of the conduit, ensuring that no other hostile mobs or skeleton horses are within that range (conduits can only damage one mob at a time).

Observed results: 

The skeleton horse takes damage from the conduit, eventually dying if not moved away from the conduit.

Expected results: 

The skeleton horse, a passive mob, does not take damage.

Notes:

This issue was originally reported at MCPE-93596, which is incomplete.

Here is a clip demonstrating the bug: https://www.xbox.com/en-US/play/media/24TM8CQV