App crashes in application:openURL:sourceApplication:annotation when returning from login with Facebook SDK. This occurs due to missing nil check.

Steps to reproduce:
1) Open the latest attached project.
2) Build for iOS.
3) Run on a device (connected to Internet).
4) Press 'FB.Init' UI button.
5) Press 'Login' button.
- The app will probably crash now if bundle ID is not set up with Facebook. If not - proceed.
6) If not already logged in, enter your FB credentials and login.

After logging in and returning to the app, a crash occurs in application:openURL:sourceApplication:annotation.

Manually adding nil check to UnityAppController.mm fixes the issue:
auto addItem = [&](NSString* key, id value)
{
[keys addObject:key];
[values addObject:value];
};

Needs to be changed to:
auto addItem = [&](NSString* key, id value) {
[keys addObject:key];
if (value == nil) {
[values addObject:[NSNull null]];
} else {
[values addObject:value];
}
};

This way, the crash doesn't occur.

Reproduced on:
5.6.0a6, 5.5.0f3

Did not reproduce:
5.4.3p2

Devices tested:
iPhone 7 iOS 10.2
iPhone 6+ iOS 10.0