Summary:
This avoids a crash when we try to load a PHAsset with nil image url. Specifically, the following condition evaluates to true when `imageURL` is nil:
```objc
if ([imageURL.scheme caseInsensitiveCompare:@"assets-library"] == NSOrderedSame) {
assetID = [imageURL absoluteString];
results = [PHAsset fetchAssetsWithALAssetURLs:@[imageURL] options:nil];
}
```
The crash will be "attempt to insert nil object from objects[0]" when we build the `@[imageURL]` array literal.
We've seen this emerge as a very common crash among Expo users, so I wanted to at least provide a clear error message instead of terminating the app.
Load an image from the photo library with a nil request url.
Closes https://github.com/facebook/react-native/pull/15952
Differential Revision: D5835219
Pulled By: ericnakagawa
fbshipit-source-id: 7be00a15e674a0905cf5c27c526ce9085d1b308f
7fab093fc8