CRASH android com.google.android.gms.location.ActivityRecognitionResult.getProbableActivities()' on a null object reference

```
java.lang.RuntimeException: An error occurred while executing doInBackground()
[ ] E/AndroidRuntime(28069): at android.os.AsyncTask$4.done(AsyncTask.java:415)
[ ] E/AndroidRuntime(28069): at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:383)
[ ] E/AndroidRuntime(28069): at java.util.concurrent.FutureTask.setException(FutureTask.java:252)
[ ] E/AndroidRuntime(28069): at java.util.concurrent.FutureTask.run(FutureTask.java:271)
[ ] E/AndroidRuntime(28069): at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167)
[ ] E/AndroidRuntime(28069): at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641)
[ ] E/AndroidRuntime(28069): at java.lang.Thread.run(Thread.java:920)
[ ] E/AndroidRuntime(28069): Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.util.List com.google.android.gms.location.ActivityRecognitionResult.getProbableActivities()' on a null object reference
[ ] E/AndroidRuntime(28069): at dk.cachet.activity_recognition_flutter.ActivityRecognizedService.onHandleIntent(ActivityRecognizedService.java:36)
[ ] E/AndroidRuntime(28069): at dk.cachet.activity_recognition_flutter.ActivityRecognizedService.onHandleWork(ActivityRecognizedService.java:30)
[ ] E/AndroidRuntime(28069): at androidx.core.app.JobIntentService$CommandProcessor.doInBackground(JobIntentService.java:396)
[ ] E/AndroidRuntime(28069): at androidx.core.app.JobIntentService$CommandProcessor.doInBackground(JobIntentService.java:387)
[ ] E/AndroidRuntime(28069): at android.os.AsyncTask$3.call(AsyncTask.java:394)
[ ] E/AndroidRuntime(28069): at java.util.concurrent.FutureTask.run(FutureTask.java:266)
```