No sub-match found.

[Bruno Verlyck <Bruno.Verlyck@inria.fr>]

With scsh-0.4.4, if I do:

   (define m (string-match "(ab)?c" "c"))
   > (match:start m 1)

I get:

   Error: #{Procedure 7851 match:start}
          "No sub-match found."
          #{regexp-match}
          1
   1> 

I see no accessible way (no module exporting a function) to know if sub-match 1
has matched nothing.  Is there another approved way I can't see or is it time
to extend scsh-regexp-interface ?

-- 
Bruno.