Catch missing classes in WorkerFactory (#3744)

When NotificationWorker was moved from ...components.notifications to
...worker.

Installing Tusky with this change doesn't remove any future periodic
jobs queued under the old class name. So when Class.forName() is
called the old class name is not found, and the exception is thrown.

Handle this the same way androidx.work.WorkerFactory does -- catch
the exception, log it, and return null.

Fixes #3740

app/src/main/java/com/keylesspalace/tusky/worker/WorkerFactory.kt

@@ -18,11 +18,13 @@
 package com.keylesspalace.tusky.worker
 
 import android.content.Context
+import android.util.Log
 import androidx.work.ListenableWorker
 import androidx.work.WorkerFactory
 import androidx.work.WorkerParameters
 import javax.inject.Inject
 import javax.inject.Provider
+import javax.inject.Singleton
 
 /**
  * Workers implement this and are added to the map in [com.keylesspalace.tusky.di.WorkerModule]
@@ -37,20 +39,33 @@ interface ChildWorkerFactory {
  * Creates workers, delegating to each worker's [ChildWorkerFactory.createWorker] to do the
  * creation.
  *
- * @see [com.keylesspalace.tusky.components.notifications.NotificationWorker]
+ * @see [com.keylesspalace.tusky.worker.NotificationWorker]
  */
+@Singleton
 class WorkerFactory @Inject constructor(
-    val workerFactories: Map<Class<out ListenableWorker>, @JvmSuppressWildcards Provider<ChildWorkerFactory>>
+    private val workerFactories: Map<Class<out ListenableWorker>, @JvmSuppressWildcards Provider<ChildWorkerFactory>>
 ) : WorkerFactory() {
     override fun createWorker(
         appContext: Context,
         workerClassName: String,
         workerParameters: WorkerParameters
     ): ListenableWorker? {
-        val key = Class.forName(workerClassName)
+        val key = try {
+            Class.forName(workerClassName)
+        } catch (e: ClassNotFoundException) {
+            // Class might be missing if it was renamed / moved to a different package, as
+            // periodic work requests from before the rename might still exist. Catch and
+            // return null, which should stop future requests.
+            Log.d(TAG, "Invalid class: $workerClassName", e)
+            null
+        }
         workerFactories[key]?.let {
             return it.get().createWorker(appContext, workerParameters)
         }
         return null
     }
+
+    companion object {
+        private const val TAG = "WorkerFactory"
+    }
 }