panic: Assertion lock == sq->sq_lock failed at /usr/src-13/sys/kern/subr_sleepqueue.c:371

[Grzegorz Junka]

cpuid = 3

time = 1588422616

KDB: stack backtrace:

db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame 
0xfffffe00b27e86b0

vpanic() at vpanic+0x182/frame 0xfffffe00b27e8700

panic() at panic+0x43/frame ...

sleepq_add()

...

I see

db>

in the terminal. I tried "dump" but it says, Cannot dump: no dump device 
specified.

Is there a guide how to deal wit those, i.e. to gather information 
required to investigate issues?