node-manta#400: msync --completion returns error if manta env vars are unset node-manta#401: Newer npm breaks make cutarelease

[bahamat]

Fixes #400, #401.

Testing:

$ env | grep MANTA
$ make test TEST_FILTER=unit
test/unit/completion.test.js ........................ 54/54
test/unit/options.test.js ........................... 60/60
test/unit/trackmarker.test.js ....................... 73/73
test/unit/utils.test.js ............................. 32/32
total ............................................. 219/219

  219 passing (4s)

  ok
$ ./bin/msync --completion | head
#!/bin/bash
#
# Bash completion generated for 'msync' at Mon Sep 18 2023 16:17:55 GMT-0700 (Pacific Daylight Time).
#
# The original template lives here:
# https://github.com/trentm/node-dashdash/blob/master/etc/dashdash.bash_completion.in
#

#
# Copyright 2016 Trent Mick

The changes for make cutarelease were used to publish the last release.