bug#25883: 25.2; Frequent, but not reproducible, crash on startup

[Eli Zaretskii <eliz@gnu.org>]

> From: John Wiegley <jwiegley@gmail.com>
> Cc: bug-gnu-emacs@gnu.org
> Date: Sun, 26 Feb 2017 11:45:45 -0800
> 
> >>>>> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > I am not familiar enough with ERC support in Emacs -- is it possible that
> > Emacs tries to display some partial byte stream that includes incomplete
> > characters, i.e. the byte sequence for some character(s) is incomplete?
> 
> Not only possible, but likely.  What happens is this:
> 
>   1. Emacs starts up
>   2. ERC begins initializing
>   3. ERC logins in to ZNC
>   4. ZNC starts playing black all the messages that came in since I last
>      exited Emacs.
>   5. Emacs sometimes survives this, sometimes crashes.
> 
> So it's quite possible that a "past message" ZNC is playing back contains a
> partial byte sequence.

It's important to have the text of the buffer at the point of crash.
I could tell you how to do that with GDB, but I don't know how with
other debuggers.

Does ERC display include overlays or display strings or images?  Or
maybe (space . PROPS) display properties?  Or any other kind of
non-buffer text?