Revert "Remove error serialization/deserialization (#3110)" (#3151)

This reverts commit 76ac9419b8.

keychain/src/extkey_bip32.rs

@@ -295,7 +295,7 @@ impl serde::Serialize for ChildNumber {
 }
 
 /// A BIP32 error
-#[derive(Clone, PartialEq, Eq, Debug)]
+#[derive(Clone, PartialEq, Eq, Debug, Serialize, Deserialize)]
 pub enum Error {
 	/// A pk->pk derivation was attempted on a hardened key
 	CannotDeriveFromHardenedKey,

keychain/src/mnemonic.rs

@@ -29,7 +29,7 @@ lazy_static! {
 }
 
 /// An error that might occur during mnemonic decoding
-#[derive(Debug, PartialEq, Eq, Clone)]
+#[derive(Debug, PartialEq, Eq, Clone, Serialize, Deserialize)]
 pub enum Error {
 	/// Invalid word encountered
 	BadWord(String),

keychain/src/types.rs

@@ -40,7 +40,7 @@ use byteorder::{BigEndian, ReadBytesExt, WriteBytesExt};
 // Size of an identifier in bytes
 pub const IDENTIFIER_SIZE: usize = 17;
 
-#[derive(PartialEq, Eq, Clone, Debug)]
+#[derive(PartialEq, Eq, Clone, Debug, Serialize, Deserialize)]
 pub enum Error {
 	Secp(secp::Error),
 	KeyDerivation(extkey_bip32::Error),