No viable update path from keybase 1.0.18

I am trying to update my keybase client. I am instructed to use updater, but I do not have an updater binary:

$ keybase update
NAME:
   keybase update - The updater

USAGE:
   keybase update <command> [arguments...]

COMMANDS:
   check	Trigger an update check
   run		Run the updater with custom options
   check-in-use	Check if we are in use (safe for restart)
   notify	Notify the service about an update event


$ keybase update run
This is no longer supported. See update check.

$ keybase update check
This is no longer supported. Instead you can run:

	/usr/local/Cellar/keybase/1.0.18/bin/updater check

$ ls /usr/local/Cellar/keybase/1.0.18/bin
keybase

$ keybase --version
keybase version 1.0.18

Please let me know if there is a workaround for this! I would prefer not to uninstall and reinstall because then I lose my configuration settings / login state.

Start with the keybase update command output and compare its expected /usr/local/Cellar/keybase/1.0.18/bin/updater path with the listed contents of that directory. Determine why version 1.0.18 has no viable update command, then verify that updating works without removing the existing configuration or login state.