I tried emacs '/-:|sudo::' with debug-on-error set to true in my simplified init.el. I also tried it with my regular init.el. But I'm not getting a backtrace. I did notice a few more errors. The error about custom.el is only because I deleted it. If I open emacs again, it goes away. If I insert a few blank lines at the top of init.el, the scan errors move location slightly, so it does appear to be complaining about customizations. I'm wondering if it's having some issue reading the file due to permissions or because it's on a mounted windows partition. However, I had tried it with my init.el inside the docker container. And it doesn't complain about the rest of my init.el, which is quite lengthy.
error: "Invalid face custom-changed"
Scan error: "Scan error", "Unbalanced parentheses 1 2" [3 times]
Scan error: "Scan error", "Unbalanced parentheses 3 4"
Scan error: "Scan error", "Unbalanced parentheses 1 4" [2 times]
Scan error: "Scan error", "Unbalanced parentheses 1 2" [15 times]
Scan error: "Scan error", "Unbalanced parentheses 3 4"
Scan error: "Scan error", "Unbalanced parentheses 1 4" [2 times]
Scan error: "Scan error", "Unbalanced parentheses 1 2" [12 times]
Scan error: "Scan error", "Unbalanced parentheses 3 4"
Scan error: "Scan error", "Unbalanced parentheses 1 4" [2 times]
Scan error: "Scan error", "Unbalanced parentheses 1 2" [9 times]
File is missing: Opening input file No such file or directory /mnt/home/share/.emacs.d/custom.el
(New file)