Run COALESCE on log parts aggregate

If there're no parts for a given log array_to_string will return NULL
and in consequence concatenation will also return NULL (because as it
turns out `'' || NULL` returns NULL). This theoretically shouldn't
happen, because aggregate service gets only logs that contain parts, but
if a restart is performed while the aggregate service runs, it can
potentially clear log parts for a log that is already scheduled for
aggregation.

Piotr Sarnacki authored and committed

Nothing here #1585.1 passed

  • Ran for
AMD64
no language set
Git

There was an error while trying to fetch the log.