Fix 'json-prune' — handle 'null' values while checking specified key in object #504
Description
While uBO can process m.place.naver.com##+js(json-prune, [].data.poiRecommendations.recommendations.[].items.[-].adClickLog.clickUrl), AdGuard scriptlet engine cannot understand m.place.naver.com#%#//scriptlet('json-prune', '[].data.poiRecommendations.recommendations.[].items.[-].adClickLog.clickUrl').
Related issue: AdguardTeam/AdguardFilters#204844