App Crash

[ghost]

The app crashes when I press the download button before it has loaded the newest WhatsApp version.

java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String com.javiersantos.whatsappbetaupdater.models.Update.getLatestVersion()' on a null object reference
at com.javiersantos.whatsappbetaupdater.utils.UtilsAsync$DownloadFile.onPreExecute(UtilsAsync.java:81)
at android.os.AsyncTask.executeOnExecutor(AsyncTask.java:604)
at android.os.AsyncTask.execute(AsyncTask.java:551)
at com.javiersantos.whatsappbetaupdater.activities.MainActivity.toDownload(MainActivity.java:127)
at com.javiersantos.whatsappbetaupdater.activities.MainActivity_ViewBinding$1.doClick(MainActivity_ViewBinding.java:44)
at butterknife.internal.DebouncingOnClickListener.onClick(DebouncingOnClickListener.java:22)
at android.view.View.performClick(View.java:5697)
at android.view.View$PerformClick.run(View.java:22526)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:158)
at android.app.ActivityThread.main(ActivityThread.java:7224)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1230)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1120)