Nil check for open url callback

Author: jasoncoolmax

MSALiOSB2C/AppDelegate.swift

@@ -80,7 +80,9 @@ class AppDelegate: UIResponder, UIApplicationDelegate {
 
         print("Received callback!")
 
-        MSALPublicClientApplication.handleMSALResponse(url, sourceApplication: sourceApplication!)
+        guard let sourceApp = sourceApplication else { return false }
+        
+        MSALPublicClientApplication.handleMSALResponse(url, sourceApplication: sourceApp)
 
         return true
     }