Offer::read: don't override DecodeError

Previously when reading an offer from bytes, if it resulted in a DecodeError
then that error would be overridden by DecodeError::InvalidValue specifically.
Better to return to underlying specific error.

Author: valentinewallace

lightning/src/offers/offer.rs

@@ -1039,7 +1039,10 @@ impl LengthReadable for Offer {
 		reader: &mut R,
 	) -> Result<Self, DecodeError> {
 		let bytes: WithoutLength<Vec<u8>> = LengthReadable::read_from_fixed_length_buffer(reader)?;
-		Self::try_from(bytes.0).map_err(|_| DecodeError::InvalidValue)
+		Self::try_from(bytes.0).map_err(|e| match e {
+			Bolt12ParseError::Decode(e) => e,
+			_ => DecodeError::InvalidValue,
+		})
 	}
 }