VM stack overflow while calling sxml-match within let* or car

[nalaginrut]

hi all, I found a strange problem while I's using sxml module.
For example, I have a regular xml file,and convert it to a sxml format:

---------------------------
(*TOP* (*PI* xml "version=\"1.0\" encoding=\"UTF-8\"") (note "
    " (to "Tove") "
    " (from "Jani") "
    " (heading "Reminder") "
    " (body "Don't forget me this weekend!") "
"))
---------------------------

While I's trying "sxml-match" to get some value:
=======================================
(sxml-match 
  (car ((sxpath '(note to)) nn)) 
  [(to ,cv) (list cv)] [,otherwise #f])
=======================================
The result is OK.

But I want do some extension operation, like:

============
(let* (to (sxml-match .........) ...
or
(car (sxml-match ........) ...
============

Guile will crash and say:
../../module/sxml/xpath.scm:111:0: In procedure nodeset?:
../../module/sxml/xpath.scm:111:0: Throw to key `vm-error' with args
`(vm-run "VM: Stack overflow" ())'.


Is it a bug?

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HFG - NalaGinrut