Fix lint warnings and error

modules/ui/init.js

@@ -166,7 +166,7 @@ export function uiInit(context) {
         // HACK: Mobile Safari 14 likes to select anything selectable when long-
         // pressing, even if it's not targeted. This conflicts with long-pressing
         // to show the edit menu. We add a selectable offscreen element as the first
-        // child to trick Safari into not showing the selection UI.  
+        // child to trick Safari into not showing the selection UI.
         overMap
             .append('div')
             .attr('class', 'select-trap')

modules/ui/sections/background_offset.js

@@ -25,12 +25,6 @@ export function uiSectionBackgroundOffset(context) {
     ];
 
 
-    function cancelEvent(d3_event) {
-        d3_event.stopPropagation();
-        d3_event.preventDefault();
-    }
-
-
     function updateValue() {
         var meters = geoOffsetToMeters(context.background().offset());
         var x = +meters[0].toFixed(2);

modules/ui/sidebar.js

@@ -407,7 +407,7 @@ export function uiSidebar(context) {
         resizer.on('dblclick', function(d3_event) {
             d3_event.preventDefault();
             if (d3_event.sourceEvent) {
-                e.sourceEvent.preventDefault();
+                d3_event.sourceEvent.preventDefault();
             }
             sidebar.toggle();
         });