bug#73387: 30.0.90; C-x v v in diff-mode doesn't work after C-c C-n

[Sean Whitton <spwhitton@spwhitton.name>]

Hello,

On Thu 03 Oct 2024 at 09:33am +03, Eli Zaretskii wrote:

>> From: Sean Whitton <spwhitton@spwhitton.name>
>> Cc: dgutov@yandex.ru,  73387@debbugs.gnu.org,  monnier@iro.umontreal.ca,
>>   juri@linkov.net
>> Date: Thu, 03 Oct 2024 08:50:37 +0800
>>
>> >   @item C-c @key{RET} k
>> >   Delete diff hunks other than the current one.  If the region is
>> >   active, this command deletes the hunks overlapped by the region;
>> >   otherwise it deletes all the hunks other than the current hunk.  Do
>> >   @emph{not} invoke this command in a narrowed buffer, as that could
>> >   produce unexpected results.
>>
>> Okay, I've rewritten based on this, though I haven't included the
>> imprecation, because invoking it in a narrowed buffer could never
>> produce unexpected results -- the function will always do nothing.
>
> Then why do we signal user-error in that case?  I think this should be
> explained in the manual.

I think I am using user-error wrongly.

Shall I just switch it to 'message', and rearrange the control flow so
nothing else happens?

-- 
Sean Whitton