"No space left on device" despite plenty left

[xerz-one]

Despite having ~70GB of internal storage free and plenty of free RAM, Customizer stops and freezes during the generation of the initramfs, consuming all CPUs in the process, after it reports that

mount: /home/customizer/FileSystem/tmp: mount (2) system call failed: No space left on device.

This makes me unable to create any custom ISO. I'm using the latest version compiled from Git on an up-to-date Debian Sid. Machine is a Surface Pro 5 with 256GB of internal storage and 8GB of RAM.

Below there's two screenshots of two different times where this happened.

[kamilion]

Can you enable the debug output and attach it?
Sounds like issue 207.
#207 (comment)

Easiest workaround is to reboot the system to clear out the screwy bind mount tree.
https://unix.stackexchange.com/questions/529478/enospc-when-binding-root-in-chroot#comment979821_529478

This is why I use a build VM to generate ISOs consistently.
Also, I "can't" support debian sid, so any issues that arise from that are yours to keep. :)
Buster's the latest supported debian that I've tested against in the past.

Something is amiss with your system's ability to unmount a bind mount.
Could be one of the sid packages, I have no method of verification.

[tawfiknasser]

$ sudo customizer --clean
or clean delete the related files manually.
and yes use a Virtual Machine to avoid any possible damage