Kind of remind me of GWT Compile Java to Javascript.

In order for "debug" (not just writing/copy-paste some demo code) any "real" project with that, you have to to be expert in Java, Javascript and all the tiniest details of GWT framework. Any crash, stack trace involve stack trace thru the JAVA framework, javascript stack and all the wonderful translation, compilations, VM layers.

The only few programmers who can really do that is probably the few folks who wrote GWT.

Have been programming C, Linux Kernel Driver, Embeded, VB, Tcl, Python, Android/Java, JS, SQL, for past 20+ years, one thing I still love is KISS - Keep It Simple Stupid.