bug#20966: 25.0.50; `button-at': (wrong-type-argument integer-or-marker-p nil), and *Backtrace* broken

[Lars Ingebrigtsen <larsi@gnus.org>]

Drew Adams <drew.adams@oracle.com> writes:

> Double regression, it seems.  Perhaps this has been fixed since this
> build, but I cannot find a Windows binary that is more recent, so I
> can't get beyond this.
>
> 1. Non-nil debug-on-error gives a _completely empty *Backtrace* buffer_,
> except for the first line, which says "Debugger entered--Lisp error:
> (args-out-of-range 20324)".  I've never seen that before, but I get it
> consistently with this build.
>
> 2. So I tried `M-x debug-on-entry describe-function-1', to see what
> went wrong.  Here's a backtrace, from using `describe-function':
>
> Debugger entered--Lisp error: (wrong-type-argument integer-or-marker-p nil)
> * get-char-property(nil button)
> * button-at(nil)
> * help-xref-button(1 help-function-def icicle-highlight-input-noncompletion=
>  "d:/usr/drew/drews-lisp-20/icicles-fn.el")

Do you have a recipe to reproduce this bug?

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   bloggy blog: http://lars.ingebrigtsen.no