bug#67196: M-: uses a wrong value of debug-on-error when it is nil.

[Eli Zaretskii]

> Date: Fri, 24 Nov 2023 17:10:47 +0000
> Cc: Eli Zaretskii <eliz@gnu.org>, 67196@debbugs.gnu.org
> From: Alan Mackenzie <acm@muc.de>
> 
> Firstly, though, there is a bug in the doc string of
> eval-expression-debug-on-error: rather than stating what the meaning of
> the variable is, what it's for, it states the low level details of how
> it achieves the desired effect.  This is needlessly restrictive.  I
> propose changing that doc string from:
> 
>     If non-nil set `debug-on-error' to t in `eval-expression'.
>     If nil, don't change the value of `debug-on-error'.
> 
> to something like:
> 
>     Non-nil means enter debugger on an error in a call from `eval-expression'.
>     Does not apply to errors handled by `condition-case' or those
>     matched by `debug-ignored-errors'.
>     A nil value for this variable will not prevent an entry to
>     the debugger caused by other variables such as `debug-on-error'.

First, the last two sentences above should be transposed, as the
second one is not related to the 1st one, but the 3rd one is.

And second, please try to reword so that the text is less complicated
and easier to understand.

Thanks.