Fixes Issue with flatlist

Author: riteshshukla04

packages/react-native/Libraries/Lists/FlatList.js

@@ -669,7 +669,7 @@ class FlatList<ItemT = any> extends React.PureComponent<FlatListProps<ItemT>> {
       : {renderItem: renderProp};
   };
 
-  _getStickyHeaderIndices: Array<number> | void =
+  _getStickyHeaderIndices: ?$ReadOnlyArray<number> =
     this._getItemCount(this.props.data) > 0
       ? this.props.stickyHeaderIndices
       : [];