null is not an object (evaluating 'this._listRef.scrollToIndex')

Since switching from ListView to FlatList we’re getting some errors like this:

null is not an object (evaluating 'this._listRef.scrollToIndex')

They happen rarely, but I could confirm that this also happened on one of my devices (OnePlus 3 with Android 7). The app shutted down after I’ve tried to open a view with a FlatList in it. Sadly I wasn’t able to reproduce it.

This is the full output:

TypeError null is not an object (evaluating 'this._listRef.scrollToIndex') 
    index.android.bundle:207:2069 value
    index.android.bundle:817:11813 value
    index.android.bundle:817:3218 
    index.android.bundle:39:562 
    index.android.bundle:32:664 callTimer
    index.android.bundle:32:1084 callTimers
    index.android.bundle:30:3208 value
    index.android.bundle:30:959 
    index.android.bundle:30:2640 value
    index.android.bundle:30:931 value

Due to our logs it only happens on Android devices. We are on React Native 0.46 and react-navigation for our routes. Maybe the view is destroyed while RN tries to access this._listRef?

[jasongrishkoff]

Also seeing this error pop up in my Android crash logs.

[dnish]

@charpeni Does this really need a repo when it appears in the error logs of Bugsnag? I’m just wondering, when I take a look into https://github.com/facebook/react-native/blob/d1372faeb5f9ebc87a8dc9b8c9f31590bda414ea/Libraries/Lists/FlatList.js#L395 there are a checks for this._listRef.

 if (this._listRef) {
      return this._listRef.getScrollableNode();
}

But this check is missing in https://github.com/facebook/react-native/blob/d1372faeb5f9ebc87a8dc9b8c9f31590bda414ea/Libraries/Lists/FlatList.js#L342

I guess there is a reason why we need to check for this._listRef in the other functions? So maybe someone forgot to check for it also in scrollToIndex.