How to make emrun print exceptions in stderr and exit with a suitable exit code?

[jspanchu]

I've just started looking into emrun to run the rendering test suite in vtk https://gitlab.kitware.com/vtk/vtk. It's really good. The return of exit codes, piping of stderr/stdout to the terminal is convenient. Combined with shell.html, this is a great tool for automated testing.

Although, when an uncaught exception occurs, something unexpected happens.
I would expect that emrun prints the uncaught exception message and receives a non-zero exit code from the web page.

minimal example:

// main.c
#include <stdlib.h>
int main()
{
  int(*a)() = NULL;
  int b = a();
  return b;
}

emcc -o index.html --emrun ./main.c  && emrun ./index.html

Here's the error message:

index.js:53 Uncaught RuntimeError: null function or function signature mismatch
    at index.wasm:0x1cc
    at index.wasm:0x1f6
    at index.js:678:12
    at callMain (index.js:1400:15)
    at doRun (index.js:1450:23)
    at index.js:1461:7

I've more questions about running emrun in parallel. The idea is to pass --port=0 for emrun so that any available port is used for a single emrun invocation. In theory, I could not use --kill-exit to leave the browser open but I will still need PID of the browser to close it after ctest completes.