In GNU Emacs 23.0.60.23 (i686-pc-linux-gnu, GTK+ Version 2.12.9)
 of 2008-12-12 on escher

1. emacs -Q
2. C-h f declare-function RET
3. Click or type RET on the link `elisp(Declaring Functions)' at the
   end of the *Help* buffer, to visit the Elisp info file.
==>
Emacs signals the error "byte-code: No such node or anchor:
elisp(Declaring Functions)" and the *Help* buffer switches to an *info*
buffer containing the raw text of /usr/local/info/emacs (not elisp!).
This buffer is in Info-mode but it is wholely unpropertized and the
header line is present but empty.

This is completely reproducible.  However, when I enable debug-on-error
and repeat the above steps, it does not generate a backtrace, despite
signalling the error.  (Why?  Is this a (different) bug?)  But when I
then immediately switch from the raw *info* buffer back to the *Help*
buffer again and type RET on the link, I get another error, with the
following backtrace (but only if I do not kill the *info* buffer):