From 3d65dd89037b575b0160a365ba1952d6fc876141 Mon Sep 17 00:00:00 2001
From: Bryan Housel <bryan@mapbox.com>
Date: Tue, 6 Nov 2018 14:16:23 -0500
Subject: [PATCH] preventDefault on sourceEvent, if present This prevents a
 crash when d3_event is not the actual event, but is a transition event or
 similar

---
 modules/ui/sidebar.js | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/modules/ui/sidebar.js b/modules/ui/sidebar.js
index 660d3b3b4..96ed54af7 100644
--- a/modules/ui/sidebar.js
+++ b/modules/ui/sidebar.js
@@ -223,8 +223,11 @@ export function uiSidebar(context) {
 
 
         sidebar.toggleCollapse = function(shouldCollapse) {
-            if (d3_event) {
-                d3_event.preventDefault();
+            var e = d3_event;
+            if (e.sourceEvent) {
+                e.sourceEvent.preventDefault();
+            } else if (e) {
+                e.preventDefault();
             }
 
             var container = d3_select('#id-container');