Erreur lors du calcul des statistiques

[athimel]

java.lang.RuntimeException: Unable to start activity ComponentInfo{org.zoumbox.tarot/org.zoumbox.tarot.PartyStatistics}: java.lang.NullPointerException: Attempt to invoke interface method 'java.util.Set java.util.Map.entrySet()' on a null object reference
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2464)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2524)
    at android.app.ActivityThread.access$900(ActivityThread.java:154)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1391)
    at android.os.Handler.dispatchMessage(Handler.java:102)
    at android.os.Looper.loop(Looper.java:234)
    at android.app.ActivityThread.main(ActivityThread.java:5526)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
Caused by: java.lang.NullPointerException: Attempt to invoke interface method 'java.util.Set java.util.Map.entrySet()' on a null object reference
    at com.google.common.collect.AbstractMapBasedMultiset.entryIterator(AbstractMapBasedMultiset.java:86)
    at com.google.common.collect.AbstractMultiset$EntrySet.iterator(AbstractMultiset.java:195)
    at org.zoumbox.tarot.engine.Statistics.getFavoriteContract(Statistics.java:83)
    at org.zoumbox.tarot.PartyStatistics.onCreate(PartyStatistics.java:103)
    at android.app.Activity.performCreate(Activity.java:6285)
    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1108)
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2417)
    ... 9 more