message: Handle all variants of phase and caller explicitly.
diff: @@ -114,7 +114,13 @@ pub trait Mint: RuntimeProvider + StorageProvider + SystemProvider {
  }
  }
  }
  - _ => {}
  + (
  + Phase::System | Phase::Payment | Phase::Session | Phase::FinalizePayment,
  + Some(&CallStackElement::Session { .. })
  + | Some(&CallStackElement::StoredSession { .. })
  + | Some(&CallStackElement::StoredContract { .. })
  + | None,
  + ) => {}
  }
  if !source.is_readable() {
  