Try to avoid segfault with heartbeat

Try to avoid segfault with heartbeat

Strange segfault on Redhat 7

[Thread debugging using libthread_db enabled]
$3 = 0x2521158 "bacula-fd"
$7 = 0x7f41dbe8b369 "12.7.6 (22 April 2021)"
$8 = 0x7f41dbe8bb30 "x86_64-redhat-linux-gnu-bacula-enterprise"
$9 = 0x7f41dbe8b354 "redhat"
$10 = 0x7f41dbe8b362 "(Core)"
TestName = regexwhere-test

Thread 4 (Thread 0x7f41d6ed2700 (LWP 4146)):

Thread 3 (Thread 0x7f41d76d3700 (LWP 4163)):

Thread 2 (Thread 0x7f41d64be700 (LWP 4166)):

Attempt to dump locks
Attempt to dump current JCRs. njcrs=1
threadid=0x7f41d76d3700 JobId=6 JobStatus=T jcr=0x7f41cc00f918 name=JobE.2021-04-22_13.07.30_09
        use_count=1 killable=1
        JobType=R JobLevel=
        sched_time=22-Apr-2021 13:07 start_time=22-Apr-2021 13:07
        end_time=31-Dec-1969 19:00 wait_time=31-Dec-1969 19:00
        db=(nil) db_batch=(nil) batch_started=0