*anyopaque struct members aren't checked for null pointers

[MGilleronFJ]

In Raylib, Image.data can be checked for null in case loading an image failed: https://github.com/raysan5/raylib/blob/9a280cda0be211ee751cdb44fedab8f1e698be2a/src/rtextures.c#L4156

But in the bindings, data is *anyopaque, and Zig seems to not allow comparing it with null. Maybe it should be ?*anyopaque? Or loadImage could return an error? (depending on how thin the bindings should be)

[Not-Nik]

I think returning an error would me more "Zig like", but it requires creating an extra struct for each type this affects. These are

• Image
• Wave
• Music

I'll see if I can come up with an elegant solution for this, without requiring much manual intervention