NullPointer after click on icon of ActionBar

[slumdroid]

WikiCFP version used is 1.1.2 (the latest version on the market! ).
Application crashes with the following stack trace after seeing a search result, I clicked on the icon of the actionbar, the crash does not occur if you press the back button.

E/AndroidRuntime( 3123): FATAL EXCEPTION: main
E/AndroidRuntime( 3123): java.lang.RuntimeException: Unable to start activity ComponentInfo{net.kuratkoo.wikicfp/net.kuratkoo.wikicfp.CategoryActivity}: java.lang.NullPointerException
E/AndroidRuntime( 3123): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
E/AndroidRuntime( 3123): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
E/AndroidRuntime( 3123): at android.app.ActivityThread.access$600(ActivityThread.java:141)
E/AndroidRuntime( 3123): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
E/AndroidRuntime( 3123): at android.os.Handler.dispatchMessage(Handler.java:99)
E/AndroidRuntime( 3123): at android.os.Looper.loop(Looper.java:137)
E/AndroidRuntime( 3123): at android.app.ActivityThread.main(ActivityThread.java:5041)
E/AndroidRuntime( 3123): at java.lang.reflect.Method.invokeNative(Native Method)
E/AndroidRuntime( 3123): at java.lang.reflect.Method.invoke(Method.java:511)
E/AndroidRuntime( 3123): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
E/AndroidRuntime( 3123): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
E/AndroidRuntime( 3123): at dalvik.system.NativeStart.main(Native Method)
E/AndroidRuntime( 3123): Caused by: java.lang.NullPointerException
E/AndroidRuntime( 3123): at net.kuratkoo.wikicfp.CategoryActivity.onCreate(CategoryActivity.java:35)
E/AndroidRuntime( 3123): at android.app.Activity.performCreate(Activity.java:5104)
E/AndroidRuntime( 3123): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
E/AndroidRuntime( 3123): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
E/AndroidRuntime( 3123): ... 11 more