Fixed averaging interpolating function.

src/actors.js

@@ -49,7 +49,7 @@ function getLongest(items) {
 }
 
 function getAverage(items) {
-	return Math.round(items.reduce((acc, item) => acc + item, 0) / items.length);
+	return Math.round(items.reduce((acc, item) => acc + item, 0) / items.length) || null;
 }
 
 function toBaseActors(actorsOrNames, release) {