have started looking at decompiling ELISP bytecode using the techniques
from uncompyle6 <https://pypi.python.org/pypi/uncompyle6> .

So far the results are promising. Of course one isn't going to get the
exact source text back.

For the bytecode for source text

   (setq a nil)
   (setq b nil)

when decompiled gives the equivalent:

      (setq a (setq b nil))

And macros will be in their expanded form. But I believe nevertheless
programmers will have a very good idea of what was going on when an error
was raised.