fix: throw null receiver when singleton is null on Android 9 (#112)

yukihookapi-core/src/main/java/com/highcapable/yukihookapi/hook/xposed/parasitic/AppParasitics.kt

@@ -509,6 +509,7 @@ internal object AppParasitics {
                 ?.optional(silent = true)
                 ?.firstFieldOrNull { name = "IActivityTaskManagerSingleton" }
                 ?.get()
+            singleton?.let {
                 SingletonClass.resolve()
                     .processor(AndroidHiddenApiBypassResolver.get())
                     .optional(silent = true)
@@ -520,6 +521,7 @@ internal object AppParasitics {
                 mInstance2?.let {
                     mInstanceResolver2.set(IActivityManagerProxyImpl.createWrapper(IActivityTaskManagerClass, it))
                 }
+            }
             isActivityProxyRegistered = true
         }.onFailure { YLog.innerE("Activity Proxy initialization failed because got an exception", it) }
     }