Fix #24053 prevent division by zero error in VirtualizedList debug overlay (#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: https://github.com/facebook/react-native/pull/24058

Differential Revision: D14538317

Pulled By: cpojer

fbshipit-source-id: 7b17bf51c388561c517bab1f775a31200abdc5a9
This commit is contained in:
Bartol Karuza 2019-03-20 01:38:03 -07:00 коммит произвёл Facebook Github Bot
Родитель 7ae90408c9
Коммит 02e8e531dd
1 изменённых файлов: 2 добавлений и 1 удалений

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@ -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++) {