From bd8f55dbb5f619348adfdb4efd1a65ceb52fbe76 Mon Sep 17 00:00:00 2001
From: Kris Nuttycombe <kris@nutty.land>
Date: Wed, 13 Dec 2023 11:31:58 -0700
Subject: [PATCH] Move an expectation to the site where its invariant is
 enforced.

---
 src/builder.rs | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/src/builder.rs b/src/builder.rs
index be084af..ff209fe 100644
--- a/src/builder.rs
+++ b/src/builder.rs
@@ -93,10 +93,8 @@ impl SpendDescriptionInfo {
 
     fn build<Pr: SpendProver>(
         self,
-        anchor: Option<bls12_381::Scalar>,
+        anchor: bls12_381::Scalar,
     ) -> Result<SpendDescription<InProgress<Unproven, Unsigned>>, Error> {
-        let anchor = anchor.expect("Sapling anchor must be set if Sapling spends are present.");
-
         // Construct the value commitment.
         let cv = ValueCommitment::derive(self.note.value(), self.rcv.clone());
 
@@ -471,7 +469,12 @@ impl SaplingBuilder {
         // Create the unauthorized Spend and Output descriptions.
         let shielded_spends = spend_infos
             .into_iter()
-            .map(|a| a.build::<SP>(self.anchor))
+            .map(|a| {
+                a.build::<SP>(
+                    self.anchor
+                        .expect("Sapling anchor must be set if Sapling spends are present."),
+                )
+            })
             .collect::<Result<Vec<_>, _>>()?;
         let shielded_outputs = output_infos
             .into_iter()