Here is what I see:
Dec 3 17:21:03 Serverbrain3 unassigned.devices: Disk with serial 'KINGSTON_SA2000M8500G_50026B728269650F', mountpoint 'KINGSTON_SA2000M8500G_50026B728269650F-part1' is not set to auto mount.
Dec 3 17:21:03 Serverbrain3 emhttpd: Warning: syntax error, unexpected end of file, expecting TC_DOLLAR_CURLY or TC_QUOTED_STRING or '"' in Unknown on line 31
Dec 3 17:21:03 Serverbrain3 emhttpd: in /usr/local/emhttp/plugins/unassigned.devices/include/lib.php on line 1942
Dec 3 17:21:03 Serverbrain3 unassigned.devices: Disk '/dev/nvme0n1' does not have a serial number and cannot be mounted.
Dec 3 17:21:03 Serverbrain3 unassigned.devices: Disk with serial 'KINGSTON_SA2000M8500G_50026B728269650F', mountpoint 'KINGSTON_SA2000M8500G_50026B728269650F-part3' is not set to auto mount.
It doesn't look like udev is finding a serial number on the disk /dev/nvme0n1. See if the serial number shows on the base Unraid unassigned disks page.
As for the php error, it's not very graceful when udev doesn't provide the information requested. Before you reboot the server go to a command line and give me the output of this command:
/sbin/udevadm info --query=property --path $(/sbin/udevadm info -q path -n /dev/nvme0n1)
I'll try to come up with a graceful way of handling this rather that a php error showing up.