Posting to here and to the pets mod by k1lly0u. https://umod.org/plugins/pets

Calling hook OnNpcTarget resulted in a conflict between the following plugins: Pets - False (Boolean), SleeperGuard (True (Boolean))

I went ahead and unloaded the pets mod but thought I would let you know in case either of you wanted to know and create a way for them to work together. 

In line 71 of the plugin, change True to False.
private object OnNpcTarget(BaseEntity npc, BasePlayer player) => CanIgnoreSleeper(player) ? False : Null;

Now I get the following error:

Calling hook OnNpcTarget resulted in a conflict between the following plugins: ZoneManager - True (Boolean), SleeperGuard (False (Boolean))

To be honest, this message doesn't make any sense and you can ignore it...