psql returns 0 to the shell if it finished normally, 1 if a fatal
error of its own occurs (e.g., out of memory, file not found), 2 if the connection to the server went bad and the session was not interactive, and 3 if an error occurred in a script and the variable ON_ERROR_STOP was set.
resolves #207
From psql docs (https://www.postgresql.org/docs/current/app-psql.html):
Also resolves https://github.com/juspay/services-flake/issues/107