(By Martin Haspelmath): "Negative indefinite pronouns like 'nobody', 'nothing', 'nowhere' may or may not co-occur with the ordinary marker of predicate negation. A language where they always co-occur with predicate negation is Russian... A language where negative indefinites never co-occur with predicate negation is German. In (2a-b), use of the predicate negator nicht would render the sentences ungrammatical (Niemand kam nicht; Ich habe nichts nicht gesehen)..."
It must be noted that WALS's "negative indefinite pronoun" is NOT the same as the Grammaticon's "negindefinite pronoun".