Attempt fix for cellsAroundViewport reaching out of bounds

Summary: VirtualizedList would more gracefully handle out of range cells than VirtualizedList_EXPERIMENTAL, which treats it as an invariant violation. This attempts to fix an issue where recalculation of cells around viewport can include out of range cells.

Reviewed By: rshest

Differential Revision: D39244112

fbshipit-source-id: 20fe6ea552035061d9d00720fcab77b29a785771

Author: NickGerleman

Libraries/Lists/VirtualizeUtils.js

@@ -128,7 +128,7 @@ export function computeWindowedRenderLimits(
 } {
   const itemCount = props.getItemCount(props.data);
   if (itemCount === 0) {
-    return prev;
+    return {first: 0, last: -1};
   }
   const {offset, velocity, visibleLength, zoomScale = 1} = scrollMetrics;
 

Libraries/Lists/VirtualizedList_EXPERIMENTAL.js

@@ -641,7 +641,9 @@ class VirtualizedList extends StateSafePureComponent<Props, State> {
         !this._scrollMetrics.offset &&
         Math.abs(distanceFromEnd) >= Number.EPSILON
       ) {
-        return cellsAroundViewport;
+        return cellsAroundViewport.last >= getItemCount(data)
+          ? VirtualizedList._constrainToItemCount(cellsAroundViewport, props)
+          : cellsAroundViewport;
       }
 
       newCellsAroundViewport = computeWindowedRenderLimits(