Runnong ./validate.php: In Database.php line 176: Undefined index: PRIMARY

Hi, good people!
Please, could someone help?

Running Ubuntu 16.04 on a LXC container

$ ./validate.php

Component Version
LibreNMS 1.48.1-25-g21192a9
DB Schema 2020_05_24_212054_poller_cluster_settings (168)
PHP 7.0.33-29+ubuntu16.04.1+deb.sury.org+1
MySQL 10.0.38-MariaDB-0ubuntu0.16.04.1
RRDTool 1.5.5
SNMP NET-SNMP 5.7.3

====================================

[OK] Composer Version: 1.10.7
[OK] Dependencies up-to-date.

In Database.php line 176:

Undefined index: PRIMARY

Thank you!