Code added by Babel is omitted

[erykpiast]

The concept of using source map as a source of truth about the module boundaries in the final bundle was... not the best one. There is a code which does not originate from the source code. It's added during the compilation process, ex. by Babel.

It exists in mappings returned by source map consumer, but both source and originalLine are null. Source Map Explorer presents that code as no source.

Maybe it's a time to switch the strategy and follow what Webpack Bundle Analyzer does.