bug#61151: 30.0.50; sqlite-more-p is confusing

[Eli Zaretskii <eliz@gnu.org>]

> From: Helmut Eller <eller.helmut@gmail.com>
> Cc: 61151@debbugs.gnu.org
> Date: Mon, 30 Jan 2023 07:57:09 +0100
> 
> On Sun, Jan 29 2023, Eli Zaretskii wrote:
> 
> >> On Sun, Jan 29 2023, Eli Zaretskii wrote:
> >> 
> >> >> However, sqlite-next seems to return nil once, but then it starts over.
> >> >
> >> > This should be easy to fix.
> >> 
> >> The documentation[1] also says: 
> >> 
> >>   SQLITE_DONE means that the statement has finished executing
> >>   successfully. sqlite3_step() should not be called again on this
> >>   virtual machine without first calling sqlite3_reset() to reset the
> >>   virtual machine back to its initial state.
> >> 
> >> So this would seems like prudent fix.
> >
> > What is "this"?  Signaling an error after sqlite-next returns nil?  Or
> > something else?
> 
> I meant to not call sqlite3_step again after that it has returned
> SQLITE_DONE.  Either by returning nil or signaling an error.

I went with the former.

I also documented that it returns nil when the statement finishes
execution.