DotsGradientDrawable Nullpointer exception

[yungu-kang]

Hi.
I am using this library version 4.3.
using it well. thanks.

But there is one problem.
error logs are being captured in the app I released.

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Fatal Exception: java.lang.NullPointerException
null cannot be cast to non-null type com.tbuonomo.viewpagerdotsindicator.DotsGradientDrawable
com.tbuonomo.viewpagerdotsindicator.DotsIndicator$buildOnPageChangedListener$1.onPageScrolled$viewpagerdotsindicator_release (DotsIndicator.kt:140)

I think.. the background is nullable property, the error occurred while forcibly converting it to a nonnull type.
Can you help me?