Merge pull request #1886 from zksecurity/fix/array-get

o1-labs · Oct 25, 2024 · 90743e1 · 90743e1
2 parents 3d33cb4 + 4123a24
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -17,6 +17,10 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 
 ## [Unreleased](https://github.com/o1-labs/o1js/compare/b04520d...HEAD)
 
+### Fixed
+
+- Witness generation error in `Gadgets.arrayGet()` when accessing out-of-bounds indices https://github.com/o1-labs/o1js/pull/1886
+
 ## [2.0.0](https://github.com/o1-labs/o1js/compare/7e9394...b04520d)
 
 ### Breaking Changes

diff --git a/src/lib/provable/gadgets/basic.ts b/src/lib/provable/gadgets/basic.ts
@@ -85,7 +85,7 @@ function arrayGet(array: Field[], index: Field) {
   let i = toVar(index);
 
   // witness result
-  let a = existsOne(() => array[Number(i.toBigInt())].toBigInt() ?? 0n);
+  let a = existsOne(() => array[Number(i.toBigInt())]?.toBigInt() ?? 0n);
 
   // we prove a === array[j] + z[j]*(i - j) for some z[j], for all j.
   // setting j = i, this implies a === array[i]