RE: Should nil COLLECTION element mean a "nil" candidate for completing-read? Alist doc.

[Drew Adams]

> > (completing-read "ff: " '(nil ("a") ("b)))
> 
> A nil there is simply an error.  We don't signal an error, but the
> none of the behaviors you may see is considered as a feature.

What does that mean? Are you simply saying "don't do that" - users must ensure
that there are no nil elements in the COLLECTION arg?

Or are you saying that it is a `completing-read' bug that should be fixed - it
should ignore nil elements in its COLLECTION arg, instead of treating them as
equivalent to the string "nil"?

And what about the rest of my post, regarding the doc contradictions and
confusion wrt alist elements?