Minimal reproduction attempt for issue 821 in the istanbuljs/nyc repo, which was reported with version 11.6.0 (released March 13, 2018). Everything worked as expected with version 13.3.0 (released February 14, 2019).
$ npm install
Run Unit Tests
$ npm run test:unit
Run Integration Tests
$ npm run test:integration
Run Unit & Integration Tests
$ npm test
Generate Code Coverage for Unit Tests
$ npm run coverage:unit
Generate Code Coverage for Integration Tests
$ npm run coverage:integration
Generate Code Coverage for Unit & Integration Tests
$ npm run coverage