My work laptop has been randomly shutting itself off. I came across this stackoverflow post, it said to run

log show --predicate 'eventMessage contains "Previous shutdown cause"' --last 24h

which, for me, returns

risksys  ➜ log show --predicate 'eventMessage contains "Previous shutdown cause"' --last 24h
Filtering the log data using "composedMessage CONTAINS "Previous shutdown cause""
Skipping info and debug messages, pass --info and/or --debug to include.
Timestamp                       Thread     Type        Activity             PID    TTL
2019-05-23 11:29:01.874486-0700 0xaf       Default     0x0                  0      0    kernel: (AppleSMC) Previous shutdown cause: -128
2019-05-23 11:44:49.786722-0700 0xaf       Default     0x0                  0      0    kernel: (AppleSMC) Previous shutdown cause: -128
--------------------------------------------------------------------------------------------------------------------
Log      - Default:          2, Info:                0, Debug:             0, Error:          0, Fault:          0
Activity - Create:           0, Transition:          0, Actions:           0

This, combined with these MacOS Shutdown Causes paints a pretty bleak picture: I've got RAM issues :-(