NPE in RegularEditWindow.onAttachFragment

Added exception if null, but not fixed yet.

https://www.bugsense.com/dashboard/project/98c9e403/errors/849398050

better stacktrace now: https://www.bugsense.com/dashboard/project/98c9e403/errors/1314758025

java.lang.RuntimeException: Unable to start activity ComponentInfo{net.lp.collectionista/net.lp.collectionista.ui.activities.phones.items.book.BookItemEditWindow}: java.lang.IllegalArgumentException: Done button is null.
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1651)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1667)
at android.app.ActivityThread.handleRelaunchActivity(ActivityThread.java:2836)
at android.app.ActivityThread.access$1600(ActivityThread.java:117)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:939)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:130)
at android.app.ActivityThread.main(ActivityThread.java:3687)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:507)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:878)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:636)
at dalvik.system.NativeStart.main(Native Method) Caused by: java.lang.IllegalArgumentException: Done button is null.
at net.lp.collectionista.ui.activities.phones.RegularEditWindow.onAttachFragment(Collectionista:126)
at android.support.v4.app.FragmentManagerImpl.moveToState(Collectionista:889)
at android.support.v4.app.FragmentManagerImpl.moveToState(Collectionista:1104)
at android.support.v4.app.FragmentManagerImpl.moveToState(Collectionista:1086)
at android.support.v4.app.FragmentManagerImpl.dispatchCreate(Collectionista:1879)
at android.support.v4.app.FragmentActivity.onCreate(Collectionista:215)
at net.lp.collectionista.ui.BaseActivity.onCreate(Collectionista:86)
at net.lp.collectionista.ui.BaseSinglePaneActivity.onCreate(Collectionista:34)
at net.lp.collectionista.ui.activities.phones.RegularEditWindow.onCreate(Collectionista:83)
at net.lp.collectionista.ui.activities.phones.items.book.BookItemEditWindow.onCreate(Collectionista:59)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1615)
... 12 more