From 8c55d0e07db67ab020e0c2107bc0a49be0507157 Mon Sep 17 00:00:00 2001
From: Artur Arseniev <artur.catch@hotmail.it>
Date: Thu, 10 Jun 2021 00:58:31 +0200
Subject: [PATCH] Avoid breaking toJSON with empty symbols

---
 src/dom_components/model/Component.js | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/dom_components/model/Component.js b/src/dom_components/model/Component.js
index c98709fcd..7a7abb58e 100644
--- a/src/dom_components/model/Component.js
+++ b/src/dom_components/model/Component.js
@@ -1479,7 +1479,9 @@ const Component = Backbone.Model.extend(Styleable).extend(
         const symbol = obj[keySymbol];
         const symbols = obj[keySymbols];
         if (symbols && isArray(symbols)) {
-          obj[keySymbols] = symbols.map(i => (i.getId ? i.getId() : i));
+          obj[keySymbols] = symbols
+            .filter(i => i)
+            .map(i => (i.getId ? i.getId() : i));
         }
         if (symbol && !isString(symbol)) {
           obj[keySymbol] = symbol.getId();