สมัครสมาชิกเพื่อดาวน์โหลด
it just a test mod

The core of the problem with the testlog is that you are both using SpawnPrefab to spawn a log which causes said log to run it's spawn code like normal, but then also return it in testlog's main function which will cause it to run the spawn code a second time.
This is likely to cause issues with almost any mod that uses PrefabPostInits as most are designed to only be ran once per object.