NullPointerException on app debug

[wiwie]

I'm receiving a NullPointerException upon debugging the app on my phone.

Not sure what the best way of posting the logcat is. Going to just post it as code:

06-03 00:10:47.104 10126-10126/? I/zygote64: Late-enabling -Xcheck:jni
06-03 00:10:47.508 10126-10126/org.piwigo.debug I/InstantRun: starting instant run server: is main process
06-03 00:10:47.901 10126-10153/org.piwigo.debug D/OpenGLRenderer: HWUI GL Pipeline
06-03 00:10:49.140 10126-10126/org.piwigo.debug I/TextInputLayout: EditText added is not a TextInputEditText. Please switch to using that class instead.
06-03 00:10:49.158 10126-10126/org.piwigo.debug I/chatty: uid=10276(org.piwigo.debug) identical 1 line
06-03 00:10:49.177 10126-10126/org.piwigo.debug I/TextInputLayout: EditText added is not a TextInputEditText. Please switch to using that class instead.
06-03 00:10:49.238 10126-10126/org.piwigo.debug D/ViewRootImpl[LoginActivity]: changeCanvasOpacity: opaque=false
06-03 00:10:49.254 10126-10126/org.piwigo.debug D/AndroidRuntime: Shutting down VM
06-03 00:10:49.257 10126-10126/org.piwigo.debug E/AndroidRuntime: FATAL EXCEPTION: main
    Process: org.piwigo.debug, PID: 10126
    java.lang.NullPointerException: Attempt to invoke virtual method 'void com.github.jorgecastilloprz.progressarc.ProgressArcView.stop()' on a null object reference
        at com.github.jorgecastilloprz.FABProgressCircle.hide(FABProgressCircle.java:166)
        at org.piwigo.internal.binding.adapter.FABProgressCircleBindingAdapter.setState(FABProgressCircleBindingAdapter.java:40)
        at org.piwigo.databinding.ActivityLoginBinding.executeBindings(ActivityLoginBinding.java:461)
        at android.databinding.ViewDataBinding.executeBindingsInternal(ViewDataBinding.java:379)
        at android.databinding.ViewDataBinding.executePendingBindings(ViewDataBinding.java:351)
        at android.databinding.ViewDataBinding$6.run(ViewDataBinding.java:178)
        at android.databinding.ViewDataBinding$5.onViewAttachedToWindow(ViewDataBinding.java:146)
        at android.view.View.dispatchAttachedToWindow(View.java:17456)
        at android.view.ViewGroup.dispatchAttachedToWindow(ViewGroup.java:3326)
        at android.view.ViewGroup.dispatchAttachedToWindow(ViewGroup.java:3333)
        at android.view.ViewGroup.dispatchAttachedToWindow(ViewGroup.java:3333)
        at android.view.ViewGroup.dispatchAttachedToWindow(ViewGroup.java:3333)
        at android.view.ViewGroup.dispatchAttachedToWindow(ViewGroup.java:3333)
        at android.view.ViewGroup.dispatchAttachedToWindow(ViewGroup.java:3333)
        at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1668)
        at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1392)
        at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6752)
        at android.view.Choreographer$CallbackRecord.run(Choreographer.java:911)
        at android.view.Choreographer.doCallbacks(Choreographer.java:723)
        at android.view.Choreographer.doFrame(Choreographer.java:658)
        at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:897)
        at android.os.Handler.handleCallback(Handler.java:790)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:164)
        at android.app.ActivityThread.main(ActivityThread.java:6494)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)
06-03 00:10:49.275 10126-10126/org.piwigo.debug I/Process: Sending signal. PID: 10126 SIG: 9

Googling the issue comes up with this: JorgeCastilloPrz/FABProgressCircle#24

Obviously, Piwigo-Android is calling the hide() method incorrectly. Commenting it out in fact allows me to start the app, login, and see the list of root albums.

Not sure what a proper fix of this would be. Anyone else has an idea?