This fixes a class of issues where doom-first-file-hook would fire even
for files not opened interactively (e.g. via org-agenda reading agenda
files or helpful scraping definitions from source files).
In instances like these, hooks like find-file-hook or pre-command-hook
are set to nil to speed up this process and reduce noise, but many
packages add to these hooks when they are loaded; these are lost when
their lexical values fall out of scope, leading to odd errors (like the
one in #4759).
Fixes#4759 (again)
First brought up in hlissner/doom-emacs@9f08db8
0683861f3f