java.lang.RuntimeException: Failed to call observer method

[YasserMuhamed2017]

Could anyone here to help how to solve this exception ?

E/AndroidRuntime: FATAL EXCEPTION: main Process: com.example.android.trackmysleepquality, PID: 4117 java.lang.RuntimeException: Failed to call observer method at androidx.lifecycle.ClassesInfoCache$MethodReference.invokeCallback(ClassesInfoCache.java:226) at androidx.lifecycle.ClassesInfoCache$CallbackInfo.invokeMethodsForEvent(ClassesInfoCache.java:194) at androidx.lifecycle.ClassesInfoCache$CallbackInfo.invokeCallbacks(ClassesInfoCache.java:185) at androidx.lifecycle.ReflectiveGenericLifecycleObserver.onStateChanged(ReflectiveGenericLifecycleObserver.java:37) at androidx.lifecycle.LifecycleRegistry$ObserverWithState.dispatchEvent(LifecycleRegistry.java:361) at androidx.lifecycle.LifecycleRegistry.forwardPass(LifecycleRegistry.java:300) at androidx.lifecycle.LifecycleRegistry.sync(LifecycleRegistry.java:339) at androidx.lifecycle.LifecycleRegistry.moveToState(LifecycleRegistry.java:145) at androidx.lifecycle.LifecycleRegistry.handleLifecycleEvent(LifecycleRegistry.java:131) at androidx.fragment.app.Fragment.performStart(Fragment.java:2735) at androidx.fragment.app.FragmentStateManager.start(FragmentStateManager.java:355) at androidx.fragment.app.FragmentManager.moveToState(FragmentManager.java:1192) at androidx.fragment.app.FragmentManager.addAddedFragments(FragmentManager.java:2222) at androidx.fragment.app.FragmentManager.executeOpsTogether(FragmentManager.java:1995) at androidx.fragment.app.FragmentManager.removeRedundantOperationsAndExecute(FragmentManager.java:1951) at androidx.fragment.app.FragmentManager.execPendingActions(FragmentManager.java:1847) at androidx.fragment.app.FragmentManager$4.run(FragmentManager.java:413) at android.os.Handler.handleCallback(Handler.java:873) at android.os.Handler.dispatchMessage(Handler.java:99) at android.os.Looper.loop(Looper.java:201) at android.app.ActivityThread.main(ActivityThread.java:6810) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:547) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:873) Caused by: java.lang.IllegalArgumentException: Parameter specified as non-null is null: method kotlin.jvm.internal.Intrinsics.checkParameterIsNotNull, parameter item at com.example.android.trackmysleepquality.sleeptracker.BindingUtilsKt.setSleepImage(Unknown Source:7) at com.example.android.trackmysleepquality.databinding.FragmentSleepDetailBindingImpl.executeBindings(FragmentSleepDetailBindingImpl.java:145) at androidx.databinding.ViewDataBinding.executeBindingsInternal(ViewDataBinding.java:473) at androidx.databinding.ViewDataBinding.executePendingBindings(ViewDataBinding.java:445) at androidx.databinding.ViewDataBinding$OnStartListener.onStart(ViewDataBinding.java:1687) at java.lang.reflect.Method.invoke(Native Method) at androidx.lifecycle.ClassesInfoCache$MethodReference.invokeCallback(ClassesInfoCache.java:216) at androidx.lifecycle.ClassesInfoCache$CallbackInfo.invokeMethodsForEvent(ClassesInfoCache.java:194)  at androidx.lifecycle.ClassesInfoCache$CallbackInfo.invokeCallbacks(ClassesInfoCache.java:185)  at androidx.lifecycle.ReflectiveGenericLifecycleObserver.onStateChanged(ReflectiveGenericLifecycleObserver.java:37)  at androidx.lifecycle.LifecycleRegistry$ObserverWithState.dispatchEvent(LifecycleRegistry.java:361)  at androidx.lifecycle.LifecycleRegistry.forwardPass(LifecycleRegistry.java:300)  at androidx.lifecycle.LifecycleRegistry.sync(LifecycleRegistry.java:339)  at androidx.lifecycle.LifecycleRegistry.moveToState(LifecycleRegistry.java:145)  at androidx.lifecycle.LifecycleRegistry.handleLifecycleEvent(LifecycleRegistry.java:131)  at androidx.fragment.app.Fragment.performStart(Fragment.java:2735)  at androidx.fragment.app.FragmentStateManager.start(FragmentStateManager.java:355)  at androidx.fragment.app.FragmentManager.moveToState(FragmentManager.java:1192)  at androidx.fragment.app.FragmentManager.addAddedFragments(FragmentManager.java:2222)  at androidx.fragment.app.FragmentManager.executeOpsTogether(FragmentManager.java:1995)  at androidx.fragment.app.FragmentManager.removeRedundantOperationsAndExecute(FragmentManager.java:1951)  at androidx.fragment.app.FragmentManager.execPendingActions(FragmentManager.java:1847)  at androidx.fragment.app.FragmentManager$4.run(FragmentManager.java:413)  at android.os.Handler.handleCallback(Handler.java:873)  at android.os.Handler.dispatchMessage(Handler.java:99)  at android.os.Looper.loop(Looper.java:201)  at android.app.ActivityThread.main(ActivityThread.java:6810)  at java.lang.reflect.Method.invoke(Native Method)  at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:547)  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:873)