I manually triggered it, and didn’t read the logs when it said it failed. That was my fault. If it fails, it will tell you. You still have the machine working until you reboot, so if you read the logs, you can clear /tmp and retry again, and the machine should be bootable again.

Linux lets you do anything, including stupid things. I’d say doing stupid things is the fastest way to learn about it, though.

The same issue would have happened even on Ubuntu, as it uses the same tools as Arch for generating the initramfs. I don’t consider it an Arch or Linux issue, just a user mistake. It won’t happen normally, unless you manually trigger it.