Made wrapped values of error tuple structs public

src/data/u4.rs

@@ -6,7 +6,7 @@ use core::convert::TryFrom;
 pub struct U4(u8);
 
 /// Error representing that this value is not a valid u4
-pub struct InvalidU4(u8);
+pub struct InvalidU4(pub u8);
 
 impl TryFrom<u8> for U4 {
     type Error = InvalidU4;

src/data/u7.rs

@@ -8,7 +8,7 @@ use core::convert::TryFrom;
 pub struct U7(pub(crate) u8);
 
 /// Error representing that this value is not a valid u7
-pub struct InvalidU7(u8);
+pub struct InvalidU7(pub u8);
 
 impl TryFrom<u8> for U7 {
     type Error = InvalidU7;

src/message/channel.rs

@@ -44,7 +44,7 @@ pub enum Channel {
 }
 
 /// Error indicating an invalid MIDI channel.
-pub struct InvalidChannel(u8);
+pub struct InvalidChannel(pub u8);
 
 impl TryFrom<u8> for Channel {
     type Error = InvalidChannel;