RegExChunker throws 'NullPointerException: Attempt to invoke interface method 'java.util.Iterator java.util.List.iterator()' Exception

[mathwood]

This is my code:

Event event = Apex.nlp("fa", "نهار فردا بعد از ظهر ساعت ۷");
Log.d("NLP", event.title());

and this is the exception details

java.lang.RuntimeException: Unable to start activity ComponentInfo{ir.masood.app/ir.masood.app.activities.HomeActivity}: java.lang.NullPointerException: Attempt to invoke interface method 'java.util.Iterator java.util.List.iterator()' on a null object reference
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
        at android.app.ActivityThread.-wrap11(ActivityThread.java)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
        at android.os.Handler.dispatchMessage(Handler.java:102)
        at android.os.Looper.loop(Looper.java:148)
        at android.app.ActivityThread.main(ActivityThread.java:5417)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.ZygoteInit$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.Iterator java.util.List.iterator()' on a null object reference
        at com.sixthsolution.apex.nlp.ner.regex.RegExChunker.chunk(RegExChunker.java:26)
        at com.sixthsolution.apex.nlp.parser.StandardParserBase.parse(StandardParserBase.java:49)
        at com.sixthsolution.apex.Apex.nlp(Apex.java:32)
        at ir.masood.app.activities.HomeActivity.onCreate(HomeActivity.java:397)
        at android.app.Activity.performCreate(Activity.java:6251)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476) 
        at android.app.ActivityThread.-wrap11(ActivityThread.java) 
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344) 
        at android.os.Handler.dispatchMessage(Handler.java:102) 
        at android.os.Looper.loop(Looper.java:148) 
        at android.app.ActivityThread.main(ActivityThread.java:5417)