From 4afc6d4c94e79945a8df4b1ca186025682306f2a Mon Sep 17 00:00:00 2001
From: Tony Garnock-Jones <tonyg@leastfixedpoint.com>
Date: Fri, 10 Sep 2021 15:47:16 +0200
Subject: [PATCH] Repair error in merge

---
 implementations/javascript/packages/core/src/merge.ts | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/implementations/javascript/packages/core/src/merge.ts b/implementations/javascript/packages/core/src/merge.ts
index fb8c2a8..fa8b215 100644
--- a/implementations/javascript/packages/core/src/merge.ts
+++ b/implementations/javascript/packages/core/src/merge.ts
@@ -64,8 +64,11 @@ export function merge<T>(
     }
 
     function walkMany(a: Array<Value<T>>, b: Array<Value<T>>): Array<Value<T>> {
-        if (a.length !== b.length) die();
-        return a.map((aa, i) => walk(aa, b[i]));
+        if (a.length <= b.length) {
+            return b.map((bb, i) => (i < a.length) ? walk(a[i], bb) : bb);
+        } else {
+            return a.map((aa, i) => (i < b.length) ? walk(aa, b[i]) : aa);
+        }
     }
 
     return items.reduce(walk, item0);