Hope to make Travis happier (will fail, there are other problems on Sauce Labs, but one thing at a time):
npm ERR! cipm can only install packages with an existing package-lock.json or npm-shrinkwrap.json with lockfileVersion >= 1. Run an install with npm@5 or later to generate it, then try again.
lockfile created with npm 6.4.1.
one created with npm 5 led to mysterious npm ERR! Invalid Version: https://registry.npmjs.org/chalk/-/chalk-2.3.0.tgz errors.
Hope to make Travis happier (will fail, there are other problems on Sauce Labs, but one thing at a time):
-- https://travis-ci.org/cben/mathdown/jobs/435790752
lockfile created with npm 6.4.1. one created with npm 5 led to mysterious
npm ERR! Invalid Version: https://registry.npmjs.org/chalk/-/chalk-2.3.0.tgz
errors.