static Runnable _topLevelErrorHandling(Runnable r) {
ifdef LeanMode
  ret r;
endifdef
ifndef LeanMode
  if (r == null) null;
  
  // maybe we don't want this anymore. just dm_current_generic()
  O info = _threadInfo();
  O mod = dm_current_generic();
  Runnable r2 = r;
  
  if (info != null || mod == null)
    r2 = r {
      temp (AutoCloseable) rcall enter(mod);
      _threadInheritInfo(info);
      r.run();
    };
  r2 = rPcall(r2);
  ret r2;
endifndef
}