fixup: drop nil check also in Close()

Signed-off-by: Florian Lehner <dev@der-flo.net>

Author: florianl

perf/reader.go

@@ -286,14 +286,10 @@ func (pr *Reader) Close() error {
 	defer pr.pauseMu.Unlock()
 
 	for _, ring := range pr.rings {
-		if ring != nil {
-			ring.Close()
-		}
+		ring.Close()
 	}
 	for _, event := range pr.eventFds {
-		if event != nil {
-			event.Close()
-		}
+		event.Close()
 	}
 	pr.rings = nil
 	pr.eventFds = nil