Some clients (a.k.a. NewsPlus) requests the API without some common param values (HTTP_USER_AGENT, and in certain circumstances include_empty & skip)

I patched some lines to hide the “undefined index” warnings:
warnings.patch (1.5 KB)

For users who use the external plugin api_newsplus, here is an equiv. patch:
api_newsplus.patch (2.2 KB)