Fix #24053 prevent division by zero error in VirtualizedList debug ov…

…erlay (#24058)

Summary:
This PR fixes the case where the content a VirtualizedList loads with a contentLength of 0,  causing a crash in the `renderDebugOverlay` function. The result of that crash is a red screen when turning on debug on FlatList and other VirtualizedList components as described in #24053.

[LIST] [FIX] - Fix VirtualizedList debug mode crash
Pull Request resolved: #24058

Differential Revision: D14538317

Pulled By: cpojer

fbshipit-source-id: 7b17bf51c388561c517bab1f775a31200abdc5a9

Libraries/Lists/VirtualizedList.js

@@ -1169,7 +1169,8 @@ class VirtualizedList extends React.PureComponent<Props, State> {
 
   _renderDebugOverlay() {
     const normalize =
-      this._scrollMetrics.visibleLength / this._scrollMetrics.contentLength;
+      this._scrollMetrics.visibleLength /
+      (this._scrollMetrics.contentLength || 1);
     const framesInLayout = [];
     const itemCount = this.props.getItemCount(this.props.data);
     for (let ii = 0; ii < itemCount; ii++) {