Subject: Re: bug#35273: "Marker does not point anywhere" when reading next article

From: Noam Postavsky <[email-masked]>
Date: Tue, 16 Apr 2019 08:38:20 -0400

Leah Neukirchen <[email-masked]> writes:

> If you have other ideas how I can debug it myself, please tell me.

If you can reproduce it reliably, setting (setq debug-on-signal t) just
before might help get a backtrace.

If that also doesn't work you could record the backtrace from a
signal-hook-function:

    (defvar bug-35273-last-backtrace nil)
    (defun bug-35273-record-backtrace (err data)
      (when (and (eq err 'error)
                 (equal data '("Marker does not point anywhere")))
        (setq bug-35273-last-backtrace
              (backtrace-frames 'signal)))
      (let ((signal-hook-function nil))
        (signal err data)))
    (setq signal-hook-function #'bug-35273-record-backtrace)

Or if you can run under gdb, just set a breakpoint in the C code where
that error is raised.