tapping DONE in Paypal modal crashes app

[faceyspacey]

It's occurring at this line:

https://github.com/kraffslol/react-native-braintree-xplat/blob/master/ios/RCTBraintree/RCTBraintree.m#L99

Here's the error I'm getting delivered to fabric:

Fatal Exception: NSInvalidArgumentException
0  CoreFoundation                 0x187e801c0 __exceptionPreprocess
1  libobjc.A.dylib                0x1868b855c objc_exception_throw
2  CoreFoundation                 0x187d5f600 -[__NSPlaceholderArray initWithObjects:count:]
3  CoreFoundation                 0x187d6b38c +[NSArray arrayWithObjects:count:]
4  CelebvidyDev                   0x10017df10 __41-[RCTBraintree showPayPalViewController:]_block_invoke_2 (RCTBraintree.m:92)
5  CelebvidyDev                   0x10022e348 __57-[BTPayPalDriver setAppSwitchReturnBlock:forPaymentType:]_block_invoke (BTPayPalDriver.m:338)
6  CelebvidyDev                   0x100232e98 +[BTPayPalDriver handleAppSwitchReturnURL:] (BTPayPalDriver.m:773)
7  CelebvidyDev                   0x100231a98 -[BTPayPalDriver safariViewControllerDidFinish:] (BTPayPalDriver.m:638)
8  SafariServices                 0x196108e18 -[SFSafariViewController remoteViewControllerWillDismiss:]
9  SafariServices                 0x196101318 -[SFBrowserRemoteViewController willDismissServiceViewController]
10 CoreFoundation                 0x187e86160 __invoking___
11 CoreFoundation                 0x187d79c3c -[NSInvocation invoke]
12 FrontBoardServices             0x189a21904 __FBSSERIALQUEUE_IS_CALLING_OUT_TO_A_BLOCK__
13 FrontBoardServices             0x189a21770 -[FBSSerialQueue _performNext]
14 FrontBoardServices             0x189a21b18 -[FBSSerialQueue _performNextFromRunLoopSource]
15 CoreFoundation                 0x187e2e278 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__
16 CoreFoundation                 0x187e2dbc0 __CFRunLoopDoSources0
17 CoreFoundation                 0x187e2b7c0 __CFRunLoopRun
18 CoreFoundation                 0x187d5a048 CFRunLoopRunSpecific
19 GraphicsServices               0x1897dd198 GSEventRunModal
20 UIKit                          0x18dd33818 -[UIApplication _run]
21 UIKit                          0x18dd2e550 UIApplicationMain
22 CelebvidyDev                   0x10006f5c4 main (main.m:16)
23 libdispatch.dylib              0x186d3c5b8 (Missing)

[eulo]

Duplicate #11