Export missing AfError enum as public API

Author: 9prady9

src/defines.rs

@@ -1,5 +1,5 @@
 #[repr(C)]
-#[derive(Clone, Copy)]
+#[derive(Clone, Copy, Debug)]
 pub enum AfError {
     ///
     /// The function returned successfully

src/lib.rs

@@ -31,7 +31,7 @@ mod data;
 pub use device::{get_version, info, set_device};
 mod device;
 
-pub use defines::Aftype;
+pub use defines::{Aftype, AfError};
 pub use defines::{InterpType, BorderType, MatchType, NormType};
 pub use defines::{Connectivity, ConvMode, ConvDomain, ColorSpace, MatProp};
 mod defines;