nyc coveralls integration not working - travis-ci

Question

I try to make nyc working with coveralls following the instruction:
https://github.com/istanbuljs/nyc#integrating-with-coveralls
But I can't get it to work. Here is an example repo:
https://github.com/unional/showdown-highlightjs-extension
Travis build is successful: https://travis-ci.org/unional/showdown-highlightjs-extension
And Coveralls notice the build, but does not seem to get any data:
https://coveralls.io/github/unional/showdown-highlightjs-extension
Here is my .travis.yml:
language: node_js
notifications:
email:
on_success: never
on_failure: change
node_js:
- "stable"
before_install:
- npm install -g npm
script:
- npm run verify
after_script:
- npm install coveralls && npm run coveralls
And here is my package.json:
{
...
"scripts": {
"coverage": "npm test && nyc check-coverage --branches 85 --functions 85 --lines 85",
"coveralls": "nyc report --reporter=text-lcov | coveralls",
"test": "npm run clean && tsc && nyc ava"
...
},
"nyc": {
"exclude": [
"scripts",
"**/*.spec.*",
"**/fixtures/**/*"
]
},
...
}

Answer 1

Try adding your Coveralls repo API token (which can be found on the Coveralls page for your repo) to a new COVERALLS_REPO_TOKEN encrypted environment variable on Travis, as per the (somewhat sketchy) documentation on the Coveralls site.

Answer 2

I found out the issue is in my tsconfig.json:
{
"compilerOptions": {
"sourceRoot": "/showdown-highlight-extension"
...
}
}
This setting gives me the correct (I assume) source map in the browser. See What's the proper way to set sourceRoot in typescript?
But is not liked by the coverage tool.
Once I remove it, it starts working.
Need to find an answer to that question.