InitPostEntity hooks not running traced to an addon returning a value

In #next-update, DMatter04 reported that some addons' InitPostEntity hooks added with hook.Add never run, breaking addons such as Custom FOV. homonovus suggested an addon returns a non-nil value from its hook, and Zaurzo posted a lua_run snippet to find it. On 22 Oct DMatter04 found the culprit, lua/autorun/ultrakill_test_soulorbs.lua from "[DrGBase] ULTRAKILL - Enemies - Act II & Act III", using Zaurzo's whereis tip, and Zaurzo suggested asking the author to fix it.