After yesterday's patch (6/6/2019), I received an error I hadn't before. I'm not sure what the origin is, but it appears to be between ZoneManager and BotSpawn.
The conflict warning means two plugins are trying to do different things or the same thing. In this case, they are doing the same thing, but in a different way. In public plugins, it is standard to return "true", not "false" for object hooks (like OnNpcPlayerTarget here) to avoid this conflict warning. So, the solution would be for Zone Manager to return true instead of false for this particular method.
Re: the update notes; the OnNpcPlayerTarget in the update notes is unrelated to this particular hook call and warning.