Subject: bug#21994: Possible calendar mode bug

From: Glenn Morris <[email-masked]>
Date: Mon, 07 Dec 2015 21:13:35 -0500

>> H y

The point of the cal-html package is to make an html calendar showing
your diary entries. No-one imagined it would be used without a diary.
AFAICS, that's never worked.
Anyway, I added handling for that case to the emacs-25 branch.

>> M-x diary <RET>
>> 
>> *messages* says:
>> 
>> Preparing diary...
>> diary-list-entries: Wrong type argument: stringp, nil

I can't reproduce any such issue with

rm -rf /tmp/foo
mkdir /tmp/foo
HOME=/tmp/foo emacs-24.5

My crystal ball says that you set diary-file to nil. Don't do that.
(Not sure why you would do that then call M-x diary though.)