iOS crash on scheduleNotification OnApplicationFocus

[yaKashif]

Thank you for this amazing library!

Issue:
App crashes if notification is scheduled when focused out or in on iOS.

public void OnApplicationFocus(bool hasFocus)
    {
        if(!hasFocus)
        {
                LocalNotification.SendNotification(....);
        }
    }

2019-03-14 06:54:49.214033+0500 appname[2468:1178803] Uncaught exception: NSInvalidArgumentException: *** +[NSString stringWithUTF8String:]: NULL cString
(
	0   CoreFoundation                      0x000000021c748edc <redacted> + 252
	1   libobjc.A.dylib                     0x000000021b919a40 objc_exception_throw + 56
	2   CoreFoundation                      0x000000021c64f594 <redacted> + 0
	3   Foundation                          0x000000021d0c3584 <redacted> + 92
	4   appname  			        0x00000001029f5fd8 scheduleNotification + 160
	5   appname                 		0x0000000103b66134 LocalNotification_scheduleNotification_m1D87FF490C547FDCFE9CAC0B800BA52A1D6D92E0 + 88
	6   appname                 		0x0000000103b65afc LocalNotification_SendNotification_m3A2C472D8829D79D92127D504778661B1E35FCB4 + 356
	7   appname                 		0x0000000103b687c4 LocalNotificationsManager_sendNotification_mE8B033347EDBCA808E53995CEA28D0CB28441841 + 288
	8   appname                 		0x0000000103b684f4 LocalNotificationsManager_DailyNotifications_m5DDDA1FB81255E27DD101CA2CC14386CDC6D8E69 + 4684
	9   appname				0x0000000103b2a5c0 GameDirector_OnApplicationFocus_mCA479C26545706BECFCDC3F3C207A0918A6E1B6C + 240
	10  appname				0x0000000102964768 _Z113RuntimeInvoker_TrueVoid_t22962CB4C05B1D89B55A6E1139F0E87A90987017_SByte_t9070AEA2966184235653CB9B4D33B149CDA831DFPFvvEPK10MethodInfoPvPS4_ + 72
	11  appname				0x0000000103a2b514 _ZN6il2cpp2vm7Runtime6InvokeEPK10MethodInfoPvPS5_PP15Il2CppException + 108
	12  appname				0x000000010332d53c _Z23scripting_method_invoke18ScriptingMethodPtr18ScriptingObjectPtrR18ScriptingArgumentsP21ScriptingExceptionPtrb + 100
	13  appname				0x0000000103337be0 _ZN19ScriptingInvocation6InvokeEP21ScriptingExceptionPtrb + 92
	14  appname				0x0000000103344d2c _ZN13MonoBehaviour19HandleNotificationsEPviR11MessageData + 476
	15  appname				0x0000000102de72b0 _ZN14MessageHandler13HandleMessageEPvjRK17MessageIdentifierR11MessageData + 100
	16  appname				0x0000000102de7208 _ZN10GameObject14SendMessageAnyERK17MessageIdentifierR11MessageData + 296
	17  appname				0x0000000103107f40 _Z21SendMessageToEveryoneRK17MessageIdentifier11MessageData + 216
	18  appname				0x0000000103121e14 _Z14SetPlayerFocusbb + 140
	19  appname				0x000000010246f3f0 -[UnityAppController applicationWillResignActive:] + 84
	20  appname				0x0000000103a9d310 -[OneSignalAppDelegate oneSignalApplicationWillResignActive:] + 172
	21  UIKitCore                           0x000000024964cc14 <redacted> + 868
	22  UIKitCore                           0x0000000248ef49b0 <redacted> + 1168
	23  UIKitCore                           0x0000000248ef555c _performActionsWithDelayForTransitionContext + 112
	24  UIKitCore                           0x0000000248ef44b4 <redacted> + 248
	25  UIKitCore                           0x0000000248ef93a0 <redacted> + 368
	26  UIKitCore                           0x000000024923ee60 <redacted> + 468
	27  FrontBoardServices                  0x000000021f1806e4 <redacted> + 228
	28  libdispatch.dylib                   0x000000021c182484 <redacted> + 16
	29  libdispatch.dylib                   0x000000021c125e10 <redacted> + 224
	30  FrontBoardServices                  0x000000021f1bea9c <redacted> + 40
	31  FrontBoardServices                  0x000000021f1be728 <redacted> + 416
	32  FrontBoardServices                  0x000000021f1bed44 <redacted> + 56
	33  CoreFoundation                      0x000000021c6d91f0 <redacted> + 24
	34  CoreFoundation                      0x000000021c6d9170 <redacted> + 88
	35  CoreFoundation                      0x000000021c6d8a54 <redacted> + 176
	36  CoreFoundation                      0x000000021c6d3920 <redacted> + 1040
	37  CoreFoundation                      0x000000021c6d31f0 CFRunLoopRunSpecific + 436
	38  GraphicsServices                    0x000000021e94c584 GSEventRunModal + 100
	39  UIKitCore                           0x00000002496574c0 UIApplicationMain + 212
	40  appname				0x0000000102447504 main + 212
	41  libdyld.dylib                       0x000000021c192bb4 <redacted> + 4
)

Even if I change the !hasFocus to hasFocus it still crashes.

public void OnApplicationFocus(bool hasFocus)
{
   if(hasFocus)
   {
       LocalNotification.SendNotification(....);
   }
 }

IOS 12.1.4
Unity 2018.1, 2018.3
Any ideas?