From b36b90907345751969dc91da642354d9cdd8e17a Mon Sep 17 00:00:00 2001
From: Sander Hautvast <shautvast@gmail.com>
Date: Tue, 2 Mar 2021 19:25:32 +0100
Subject: [PATCH] fixed update on lazy val evaluating to undefined

---
 src/js/index.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/js/index.js b/src/js/index.js
index b1018dd..c37ecd3 100644
--- a/src/js/index.js
+++ b/src/js/index.js
@@ -43,7 +43,7 @@ export const update_lazy_objects = function () {
         if (state[binding.name].lazy_expression) {                  // if lazy,
             let value = visit(state[binding.name].lazy_expression); // reevaluate,
             let existing_value = bindings[binding.name].evaluated;  // update view
-            if (existing_value.id) {
+            if (existing_value && existing_value.id) {
                 // update view after reevaluation of lazy vectors
                 update_vector_arrow(existing_value.id, value);
                 bindings[binding.name].evaluated = value;