From b814335b992aafe250e21bb56f5fcd5048a90309 Mon Sep 17 00:00:00 2001
From: Bruno Windels <brunow@matrix.org>
Date: Fri, 21 Aug 2020 19:21:53 +0200
Subject: [PATCH] this was missing! and causing an error with empty lists

---
 src/observable/map/MappedMap.js | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/observable/map/MappedMap.js b/src/observable/map/MappedMap.js
index 51a23d41..7b7d1583 100644
--- a/src/observable/map/MappedMap.js
+++ b/src/observable/map/MappedMap.js
@@ -79,4 +79,8 @@ export class MappedMap extends BaseObservableMap {
     [Symbol.iterator]() {
         return this._mappedValues.entries();
     }
+
+    get size() {
+        return this._mappedValues.size;
+    }
 }