Curl installer: "Distro not supported" Buster


i have an LXC-Container with Debian GNU/Linux 10 \n \l. with Proxmox.

The curl installer says:

root@nextcloudpi:~# curl -sSL | bash
Getting build code...
Hit:1 buster InRelease
Hit:2 buster-updates InRelease
Hit:3 buster/updates InRelease
Reading package lists... Done
Reading package lists... Done
Building dependency tree       
Reading state information... Done
ca-certificates is already the newest version (20190110).
sudo is already the newest version (1.8.27-1).
wget is already the newest version (1.20.1-1.1).
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
/tmp/nextcloudpi.TxgNip ~

Installing NextCloudPi...
etc/ line 277: lsb_release: command not found
ERROR: distro not supported:
Debian GNU/Linux 10 \n \l

What is wrong?