Xiaomi: check if binary parser result is null

The activity parser may return null pointers in case the version
of the data structure is not supported. Not checking for null here may
result in the activity fetching task may never complete and cause
further communication with the device to grind to a halt.

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/xiaomi/activity/impl/WorkoutSummaryParser.java

@@ -60,6 +60,11 @@ public class WorkoutSummaryParser extends XiaomiActivityParser implements Activi
             return false;
         }
 
+        // parseBinaryData may return null in case the version is not supported
+        if (summary == null) {
+            return false;
+        }
+
         summary.setSummaryData(null); // remove json before saving to database
 
         try (DBHandler dbHandler = GBApplication.acquireDB()) {