fix WorkManager exception

* Before using WorkManager, check for its existence. Else, in rare cases that caused crashing, initialize it ourselves.
* Additionally, as another layer to handling this issue, when initializing WorkManager ourselves, surround it in a try-catch as it is may be the slightest bit possible for another thread to initialize it in the interim between checking and initializing.
* Provides a method to check if WorkManager is initialized in this process.
  - This is effectively the `WorkManager.isInitialized()` public method introduced in `androidx.work:work-*:2.8.0-alpha02`.
  - Please see https://android-review.googlesource.com/c/platform/frameworks/support/+/1941186 for the library's implementation

Author: nan-li

OneSignalSDK/onesignal/notifications/src/main/java/com/onesignal/notifications/internal/common/OSWorkManagerHelper.kt

@@ -0,0 +1,46 @@
+package com.onesignal.notifications.internal.common
+
+import android.annotation.SuppressLint
+import android.content.Context
+import androidx.work.Configuration
+import androidx.work.WorkManager
+import androidx.work.impl.WorkManagerImpl
+
+object OSWorkManagerHelper {
+    /**
+     * Helper method to provide a way to check if WorkManager is initialized in this process.
+     * The purpose of this helper is to work around this bug - https://issuetracker.google.com/issues/258176803
+     *
+     * This is effectively the `WorkManager.isInitialized()` public method introduced in androidx.work:work-*:2.8.0-alpha02.
+     * Please see https://android-review.googlesource.com/c/platform/frameworks/support/+/1941186.
+     *
+     * @return `true` if WorkManager has been initialized in this process.
+     */
+    @SuppressWarnings("deprecation")
+    @SuppressLint("RestrictedApi")
+    private fun isInitialized(): Boolean {
+        return WorkManagerImpl.getInstance() != null
+    }
+
+    /**
+     * If there is an instance of WorkManager available, use it. Else, in rare cases, initialize it ourselves.
+     *
+     * Calling `WorkManager.getInstance(context)` directly can cause an exception if it is null.
+     *
+     * @return an instance of WorkManager
+     */
+    @JvmStatic
+    @Synchronized
+    fun getInstance(context: Context): WorkManager {
+        if (!isInitialized()) {
+            try {
+                // Initialization can fail if another thread initializes in the small time gap
+                // https://android.googlesource.com/platform/frameworks/support/+/60ae0eec2a32396c22ad92502cde952c80d514a0/work/workmanager/src/main/java/androidx/work/impl/WorkManagerImpl.java#177
+                WorkManager.initialize(context, Configuration.Builder().build())
+            } catch (e: IllegalStateException) {
+                // Admittedly starting to get hacky
+            }
+        }
+        return WorkManager.getInstance(context)
+    }
+}

OneSignalSDK/onesignal/notifications/src/main/java/com/onesignal/notifications/internal/generation/impl/NotificationGenerationWorkManager.kt

@@ -5,12 +5,12 @@ import androidx.work.CoroutineWorker
 import androidx.work.Data
 import androidx.work.ExistingWorkPolicy
 import androidx.work.OneTimeWorkRequest
-import androidx.work.WorkManager
 import androidx.work.WorkerParameters
 import com.onesignal.OneSignal
 import com.onesignal.common.AndroidUtils
 import com.onesignal.debug.internal.logging.Logging
 import com.onesignal.notifications.internal.common.NotificationFormatHelper
+import com.onesignal.notifications.internal.common.OSWorkManagerHelper
 import com.onesignal.notifications.internal.generation.INotificationGenerationProcessor
 import com.onesignal.notifications.internal.generation.INotificationGenerationWorkManager
 import org.json.JSONException
@@ -55,7 +55,7 @@ internal class NotificationGenerationWorkManager : INotificationGenerationWorkMa
         Logging.debug(
             "NotificationWorkManager enqueueing notification work with notificationId: $osNotificationId and jsonPayload: $jsonPayload",
         )
-        WorkManager.getInstance(context)
+        OSWorkManagerHelper.getInstance(context)
             .enqueueUniqueWork(osNotificationId, ExistingWorkPolicy.KEEP, workRequest)
 
         return true

OneSignalSDK/onesignal/notifications/src/main/java/com/onesignal/notifications/internal/receivereceipt/impl/ReceiveReceiptWorkManager.kt

@@ -7,13 +7,13 @@ import androidx.work.Data
 import androidx.work.ExistingWorkPolicy
 import androidx.work.NetworkType
 import androidx.work.OneTimeWorkRequest
-import androidx.work.WorkManager
 import androidx.work.WorkerParameters
 import com.onesignal.OneSignal
 import com.onesignal.common.AndroidUtils
 import com.onesignal.core.internal.application.IApplicationService
 import com.onesignal.core.internal.config.ConfigModelStore
 import com.onesignal.debug.internal.logging.Logging
+import com.onesignal.notifications.internal.common.OSWorkManagerHelper
 import com.onesignal.notifications.internal.receivereceipt.IReceiveReceiptProcessor
 import com.onesignal.notifications.internal.receivereceipt.IReceiveReceiptWorkManager
 import com.onesignal.user.internal.subscriptions.ISubscriptionManager
@@ -57,7 +57,7 @@ internal class ReceiveReceiptWorkManager(
         Logging.debug(
             "OSReceiveReceiptController enqueueing send receive receipt work with notificationId: $notificationId and delay: $delay seconds",
         )
-        WorkManager.getInstance(_applicationService.appContext)
+        OSWorkManagerHelper.getInstance(_applicationService.appContext)
             .enqueueUniqueWork(
                 notificationId + "_receive_receipt",
                 ExistingWorkPolicy.KEEP,

OneSignalSDK/onesignal/notifications/src/main/java/com/onesignal/notifications/internal/restoration/impl/NotificationRestoreWorkManager.kt

@@ -4,10 +4,10 @@ import android.content.Context
 import androidx.work.CoroutineWorker
 import androidx.work.ExistingWorkPolicy
 import androidx.work.OneTimeWorkRequest
-import androidx.work.WorkManager
 import androidx.work.WorkerParameters
 import com.onesignal.OneSignal
 import com.onesignal.notifications.internal.common.NotificationHelper
+import com.onesignal.notifications.internal.common.OSWorkManagerHelper
 import com.onesignal.notifications.internal.restoration.INotificationRestoreProcessor
 import com.onesignal.notifications.internal.restoration.INotificationRestoreWorkManager
 import java.util.concurrent.TimeUnit
@@ -36,7 +36,7 @@ internal class NotificationRestoreWorkManager : INotificationRestoreWorkManager
             OneTimeWorkRequest.Builder(NotificationRestoreWorker::class.java)
                 .setInitialDelay(restoreDelayInSeconds.toLong(), TimeUnit.SECONDS)
                 .build()
-        WorkManager.getInstance(context!!)
+        OSWorkManagerHelper.getInstance(context!!)
             .enqueueUniqueWork(
                 NOTIFICATION_RESTORE_WORKER_IDENTIFIER,
                 ExistingWorkPolicy.KEEP,