Workaround pending intent problem Xiaomi / Android 11

app/src/main/java/eu/faircode/email/ServiceSynchronize.java

@@ -2979,8 +2979,12 @@ public class ServiceSynchronize extends ServiceBase implements SharedPreferences
             PendingIntent pi;
             if (isBackgroundService(context))
                 pi = PendingIntentCompat.getService(context, PI_WATCHDOG, intent, PendingIntent.FLAG_UPDATE_CURRENT);
-            else
-                pi = PendingIntentCompat.getForegroundService(context, PI_WATCHDOG, intent, PendingIntent.FLAG_UPDATE_CURRENT);
+            else {
+                // Workaround for Xiaomi Android 11
+                pi = PendingIntentCompat.getForegroundService(context, PI_WATCHDOG, intent, PendingIntent.FLAG_NO_CREATE);
+                if (pi == null)
+                    pi = PendingIntentCompat.getForegroundService(context, PI_WATCHDOG, intent, PendingIntent.FLAG_UPDATE_CURRENT);
+            }
 
             AlarmManager am = (AlarmManager) context.getSystemService(Context.ALARM_SERVICE);
             am.cancel(pi);