message: Remove PurseError enum
diff: //! Home of the Mint contract's [`Error`] type.
  -use alloc::{fmt, vec::Vec};
  +use alloc::vec::Vec;
  use core::convert::{TryFrom, TryInto};
  #[cfg(feature = "std")]
  @@ -8,7 +8,7 @@ use thiserror::Error;
  use crate::{
  bytesrepr::{self, FromBytes, ToBytes, U8_SERIALIZED_LENGTH},
  - AccessRights, CLType, CLTyped,
  + CLType, CLTyped,
  };
  /// Errors which can occur while executing the Mint contract.
  @@ -90,20 +90,6 @@ pub enum Error {
  #[cfg(test)]
  const MAX_ERROR_VALUE: u8 = Error::Sentinel as u8;
  -impl From<PurseError> for Error {
  - fn from(purse_error: PurseError) -> Error {
  - match purse_error {
  - PurseError::InvalidURef => Error::InvalidURef,
  - PurseError::InvalidAccessRights(_) => {
  - // This one does not carry state from PurseError to the new Error enum. The reason
  - // is that Error is supposed to be simple in serialization and deserialization, so
  - // extra state is currently discarded.
  - Error::InvalidAccessRights
  - }
  - }
  - }
  -}
  -
  impl CLTyped for Error {
  fn cl_type() -> CLType {
  CLType::U8
  @@ -173,29 +159,6 @@ impl FromBytes for Error {
  }
  }
  -/// Errors relating to validity of source or destination purses.
  -#[derive(Debug, Copy, Clone)]
  -pub enum PurseError {
  - /// The given [`URef`](crate::URef) does not reference the account holder's purse, or such a
  - /// [`URef`](crate::URef) does not have the required [`AccessRights`].
  - InvalidURef,
  - /// The source purse is not writeable (see [`URef::is_writeable`](crate::URef::is_writeable)),
  - /// or the destination purse is not addable (see
  - /// [`URef::is_addable`](crate::URef::is_addable)).
  - InvalidAccessRights(Option<AccessRights>),
  -}
  -
  -impl fmt::Display for PurseError {
  - fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
  - match self {
  - PurseError::InvalidURef => write!(f, "invalid uref"),
  - PurseError::InvalidAccessRights(maybe_access_rights) => {
  - write!(f, "invalid access rights: {:?}", maybe_access_rights)
  - }
  - }
  - }
  -}
  -
  #[cfg(test)]
  mod tests {
  use std::convert::TryFrom;
  