Restarting MariaDB service

Dears,

we have sometimes a situation where MariaDB service is restarted in the middle of working.
In our production environment we are using one of the Percona Toolkit v3.0.12 (pt-online-schema-change) to reindex tables of our database. Sometime during this execution (not every time), MariaDB service is restarted during executing.
Last time that we faced in this problem was couple days ago and error that is appeared in MariaDB error log after 4 hours executing is:

2018-12-10 7:52:17 140406842615552 [ERROR] Got error 128 when reading table './newplatform/party_relationships'
pure virtual method called
terminate called without an active exception
181210 7:52:17 [ERROR] mysqld got signal 6 ;
This could be because you hit a bug. It is also possible that this binary
or one of the libraries it was linked against is corrupt, improperly built,
or misconfigured. This error can also be caused by malfunctioning hardware.
_To report this bug, see https://mariadb.com/kb/en/reporting-bugs_
. . .

The error gives the idea that there is a problem with this table (party_relationships), but it is not because this table is reindex sucessfully (with this job and after that manually) and the system is working also properly.

In attachment you can find complete MariaDB error log for this case and the log from executing of Percona toolkit.

MariaDB server: 10.2.19
OS: Linux-CentOS: 7.5.x

Any help for this will be appreciated.

Thanks,
Shkemb