NPE in onPreExecute

[pjv]

Bugsense: https://www.bugsense.com/dashboard/project/98c9e403/errors/1008868036

java.lang.NullPointerException
at net.lp.collectionista.util.tasks.VisibleTask.void onPreExecute()(Collectionista:120)
at net.lp.collectionista.ui.fragments.collections.CollectionExportDialog$CollectionLevelExportTask.void onPreExecute()(Collectionista:1037)
at android.os.AsyncTask.executeOnExecutor(AsyncTask.java:586)
at net.lp.collectionista.ui.fragments.collections.CollectionExportDialog$CollectionLevelExportTask.void executeHoneycomb(android.os.AsyncTask,java.lang.String[])(Collectionista:584)
at net.lp.collectionista.ui.fragments.collections.CollectionExportDialog$CollectionLevelExportTask.void start(net.lp.collectionista.ui.activities.phones.collections.CollectionExportWindow,java.lang.String)(Collectionista:575)
at net.lp.collectionista.ui.fragments.collections.CollectionExportDialog.void onClick(android.view.View)(Collectionista:386)
at android.view.View.performClick(View.java:4475)
at android.view.View$PerformClick.run(View.java:18784)
at android.os.Handler.handleCallback(Handler.java:730)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:5414)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:525)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1187)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1003)
at dalvik.system.NativeStart.main(Native Method)

[pjv (pjv)]

Added an error when we suspect getPanel() is null, to find bugs easier in the future. Not fixed yet.