Remove ZSA dummy notes

For actions made with ZSA assets, it is important not to use dummy spend
notes to ensure that the asset has been properly issued.

src/builder.rs

@@ -147,6 +147,8 @@ pub enum BuildError {
  BurnZero,
  /// The asset to be burned is duplicated.
  BurnDuplicateAsset,
+ /// There is no available split note for this asset.
+ NoSplitNoteAvailable,
 }
 
 impl Display for BuildError {
@@ -169,6 +171,7 @@ impl Display for BuildError {
  BurnNative => f.write_str("Burning is only possible for non-native assets"),
  BurnZero => f.write_str("Burning is not possible for zero values"),
  BurnDuplicateAsset => f.write_str("Duplicate assets are not allowed when burning"),
+ NoSplitNoteAvailable => f.write_str("No split note has been provided for this asset"),
  }
  }
 }
@@ -696,28 +699,34 @@ fn partition_by_asset(
  }
 
  if hm.is_empty() {
- let dummy_spend = pad_spend(None, AssetBase::native(), rng);
  // dummy_spend should not be included in the indexing and marked as None.
  hm.insert(
- dummy_spend.note.asset(),
- (vec![(dummy_spend, None)], vec![]),
+ AssetBase::native(),
+ (
+ vec![(SpendInfo::dummy(AssetBase::native(), rng), None)],
+ vec![],
+ ),
  );
  }
 
  hm
 }
 
 /// Returns the appropriate SpendInfo for padding.
-fn pad_spend(spend: Option<&SpendInfo>, asset: AssetBase, mut rng: impl RngCore) -> SpendInfo {
+fn pad_spend(
+ spend: Option<&SpendInfo>,
+ asset: AssetBase,
+ mut rng: impl RngCore,
+) -> Result<SpendInfo, BuildError> {
  if asset.is_native().into() {
  // For native asset, extends with dummy notes
- SpendInfo::dummy(asset, &mut rng)
+ Ok(SpendInfo::dummy(AssetBase::native(), &mut rng))
  } else {
- // For ZSA asset, extends with
- // - dummy note if SpendInfo is None
- // - split notes otherwise.
- let dummy = SpendInfo::dummy(asset, &mut rng);
- spend.map_or_else(|| dummy, |s| s.create_split_spend(&mut rng))
+ // For ZSA asset, extends with split_notes.
+ // If SpendInfo is none, return an error (no split note are available for this asset)
+ spend
+  .map(|s| s.create_split_spend(&mut rng))
+  .ok_or(BuildError::NoSplitNoteAvailable)
  }
 }
 
@@ -770,7 +779,11 @@ pub fn bundle<V: TryFrom<i64>, FL: OrchardFlavor>(
  let mut indexed_spends = spends
  .into_iter()
  .chain(iter::repeat_with(|| {
- (pad_spend(first_spend.as_ref(), asset, &mut rng), None)
+ (
+ pad_spend(first_spend.as_ref(), asset, &mut rng)
+ .unwrap_or_else(|err| panic!("{:?}", err)),
+ None,
+ )
  }))
  .take(num_asset_pre_actions)
  .collect::<Vec<_>>();
@@ -798,7 +811,7 @@ pub fn bundle<V: TryFrom<i64>, FL: OrchardFlavor>(
  indexed_spends_outputs.extend(
  iter::repeat_with(|| {
  (
- (pad_spend(None, AssetBase::native(), &mut rng), None),
+ (SpendInfo::dummy(AssetBase::native(), &mut rng), None),
  (OutputInfo::dummy(&mut rng, AssetBase::native()), None),
  )
  })