Reg: connection is getting closed when doing select count(*)

*I have installed Postgres12 in my Macbook. I have loaded data into the
database using pgbench. When I try to execute the command below, I am not
getting the output. Instead, connection is getting closed. Command and
errors are written below.*

*More Information:*
*I am the only one using the database with default parameters in
postgresql.conf.*

*Command:*
(base) FVFZF06NNY1J:data rkuma803$ psql -U rkuma803 -d postgres
psql (12.2)
Type "help" for help.

postgres=# \c pgbench
You are now connected to database "pgbench" as user "rkuma803".
pgbench=# *select count(*) from pgbench_accounts; *
server closed the connection
unexpectedly
This probably means the server terminated abnormally
before or while processing the request.
The connection to the server was lost. Attempting reset: Failed.
!>
!> ^D\q
(base)

*Error from DB logs,*
2020-03-03 14:59:20.868 IST [51374] STATEMENT: select count(*) from
pgbench_accounts;
2020-03-03 14:59:25.852 IST [51363] LOG: server process (PID 51386) was
terminated by signal 9: Killed: 9
2020-03-03 14:59:25.852 IST [51363] DETAIL: Failed process was running:
select count(*) from pgbench_accounts;
2020-03-03 14:59:25.852 IST [51363] LOG: terminating any other active
server processes
2020-03-03 14:59:25.854 IST [51369] WARNING: terminating connection
because of crash of another server process
2020-03-03 14:59:25.854 IST [51369] DETAIL: The postmaster has commanded
this server process to roll back the current transaction and exit, because
another server process exited abnormally and possibly corrupted shared
memory.
2020-03-03 14:59:25.854 IST [51369] HINT: In a moment you should be able
to reconnect to the database and repeat your command.