Jonathan Kyle Mitchell <kyle@jonathanmitchell.org> writes:

> Michał Kondraciuk <k.michal@zoho.com> writes:
>
>> When I evaluate this, Emacs becomes unresponsive and keeps
>> consuming 100% of my cpu:
>>
>> (progn
>>   (setq mode-line-format '(:propertize "a" face))
>>   (force-mode-line-update))
>>
>> Repository revision: ee3e432300054ca488896e39fca57b10d733330a
>
> I can also reproduce this issue on Emacs 26.1.

I compiled a debug build of Emacs 27.0.50 and took the attached
backtrace with a breakpoing on `error'.  Emacs stopped in
`validate_plist' as called from `set_text_properties' with the message
"Odd length text property list".