Fix valueForKey error in auto-tracking for screenviews (close #428)
Fix valueForKey error in auto-tracking for screenviews (close #428)

(cherry picked from commit f355226a568e7224c280cf6d03a1e7d10ab4b42c)
Previously called: “Check responds to selector instead of throwing”

snowplow/snowplow-objc-tracker,snowplow/snowplow-objc-tracker,snowplow/snowplow-objc-tracker,snowplow/snowplow-objc-tracker