Compatibility fix for Blender 2.8.1

[madhawav]

Hi,

Glad to contribute to this project again after a long break.

Today, I was trying out sphere2cube with Blender 2.81a (blender-2.81a-linux-glibc217-x86_64) and it provided me with solid magenta filled outputs instead of having the actual image. I was able to fix it with the linked code change.

I do not know whether this is a common issue others also experience.

[Xyene]

Thanks for the fix!

Would you happen to know if the required API has been around in Blender for a while, or if this would break backwards compatibility?

[madhawav]

I have only tested this on the mentioned version of blender in Linux.