startDelayedWrite catches and re-throws original

* startDelayedWrite now catches and re-throws original error thrown when Thread.start is called.
* See code comments in this commit for more details.

Author: jkasten2

OneSignalSDK/onesignal/src/main/java/com/onesignal/OneSignalPrefs.java

@@ -134,7 +134,7 @@ public static class WritePrefHandlerThread extends HandlerThread {
 
         synchronized void startDelayedWrite() {
             if (mHandler == null) {
-                start();
+                startThread();
                 mHandler = new Handler(getLooper());
             }
 
@@ -149,6 +149,41 @@ synchronized void startDelayedWrite() {
             }
         }
 
+        /**
+         * Attempt to start the thread used by this HandlerThread
+         * It may fail due to the following:
+         *   - InternalError - Thread starting during runtime shutdown
+         *   - OutOfMemoryError - pthread_create (####KB stack) failed: Try again
+         * If it does throw we want to catch then save the error and rethrow
+         * If startThread is called a 2nd time we will rethrowing the first exception
+         *   - Otherwise Thread.start will just throw IllegalThreadStateException
+         * Normally this catch and rethrow would not be needed however somewhere in this
+         *   SDK code base or a consumer of this SDK is catching first exception and
+         *   silently ignoring it. Resulting in the true causing of a crash being unknown.
+         * See https://github.com/OneSignal/OneSignal-Android-SDK/issues/917#issuecomment-600472976
+         *
+         * Future: We may want to use this strategy for all Thread.start calls.
+         *         And limit thread usages, using mostly coroutines instead.
+         */
+        private VirtualMachineError threadStartError;
+        private void startThread() {
+            if (threadStartError != null)
+                throw threadStartError;
+
+            try {
+                start();
+            } catch (InternalError e) {
+                // Thread starting during runtime shutdown
+                threadStartError = e;
+                throw e;
+            }
+            catch (OutOfMemoryError e) {
+                // pthread_create (1040KB stack) failed: Try again
+                threadStartError = e;
+                throw e;
+            }
+        }
+
         private Runnable getNewRunnable() {
             return new Runnable() {
                 @Override