Fix build error in list.js

Author: tanx

src/component/list.js

@@ -57,9 +57,9 @@ export class List extends Component {
         dataSource={this.dataSource}
         renderHeader={this.props.renderHeader}
         renderRow={data => {
-          this.props.scrollToEnd
-            ? setTimeout(() => this.list._scrollViewRef.scrollToEnd(), 50)
-            : null;
+          if (this.props.scrollToEnd) {
+            setTimeout(() => this.list._scrollViewRef.scrollToEnd(), 50);
+          }
           return this.props.renderItem(data);
         }}
         enableEmptySections={true}