office-shared-comments-ui ee041633

Author: NickGerleman

Libraries/Lists/VirtualizedList.js

@@ -777,7 +777,9 @@ class VirtualizedList extends React.PureComponent<Props, State> {
     }
 
     if (itemCount > 0) {
-      renderMask.addCells(cellsAroundViewport);
+      if (cellsAroundViewport.last >= cellsAroundViewport.first) {
+        renderMask.addCells(cellsAroundViewport);
+      }
 
       // The initially rendered cells are retained as part of the
       // "scroll-to-top" optimization
@@ -968,7 +970,7 @@ class VirtualizedList extends React.PureComponent<Props, State> {
     );
 
     return {
-      cellsAroundViewport: prevState.cellsAroundViewport,
+      cellsAroundViewport: constrainedCells,
       renderMask: VirtualizedList._createRenderMask(newProps, constrainedCells),
     };
   }