To be completed query can select invalid records

[CloCkWeRX]

What

See https://world.openfoodfacts.org/state/to-be-completed/31343 and the following pages, a number of items are presented with NULL ids.

Unsure if these are deleted items or something else.

[CharlesNepote]

I can reproduce and confirm. This doesn't seem to be very important for users.

It needs investigations to see if it matters for data quality.

TODO:

• find products without "code" in the database exports
• find possibilities to enter products without "code" (API ?)
• ask @stephanegigandet if he can find products without "code" in the live database

[hangy]

I think this is probably a duplicate of #310

The page that is mentioned in the original query works now, but the last pages still produce empty pages.