Gotcha: Yarn may need an empty `NPM_TOKEN` set to run

Earlier today I was working with a Yarn codebase for the first time on one of my machines, and I hit an awkward error I'd not seen before: % yarn install yarn install v1.22.22 error Error: Failed to replace env in config: ${NPM_TOKEN} at /usr/lib/node_modules/yarn/lib/util/env-replace.js:19:13 at String.replace (<anonymous>) at envReplace (/usr/lib/node_modules/yarn/lib/util/env-replace.js:14:16) at NpmRegistry.normalizeConfig (/usr/lib/node_modules/yarn/lib/registries/npm-registry.js:423:69) at /usr/lib/node_modules/yarn/lib/registries/npm-registry.js:455:36 at Generator.next (<anonymous>) at step (/usr/lib/node_modules/yarn/node_modules/babel-runtime/helpers/asyncToGenerator.js:17:30) at /usr/lib/node_modules/yarn/node_modules/babel-runtime/helpers/asyncToGenerator.js:28:13 info Visit https://yarnpkg.com/en/docs/cli/install for documentation about this command. A quick search online showed that this is a long-standing issue and can be fixed by exporting an empty NPM_TOKEN…