Enable Sass sourcemap in Ionic 2/3

By default, Ionic only enable sourcemap for .ts file and disable for .sass (https://github.com/driftyco/ionic-app-scripts/blob/master/config/sass.config.js#L16).

So, if you want to enable and debug your stylesheets file, just follow 2 steps:

Create config/sass.config.js

module.exports = {
  sourceMap: true,
}

Update package.json

"config": {
  "ionic_sass": "./config/sass.config.js",
},

And just re-run ionic serve command.