Connection.loadFromURL was swallowing all the errors instead of passing them along

js/id/core/connection.js

@@ -42,10 +42,10 @@ iD.Connection = function() {
     };
 
     connection.loadFromURL = function(url, callback) {
-        function done(dom) {
-            return callback(null, parse(dom));
+        function done(err, dom) {
+            return callback(err, parse(dom));
         }
-        return d3.xml(url).get().on('load', done);
+        return d3.xml(url).get(done);
     };
 
     connection.loadEntity = function(id, callback) {
@@ -137,7 +137,7 @@ iD.Connection = function() {
     };
 
     function parse(dom) {
-        if (!dom || !dom.childNodes) return new Error('Bad request');
+        if (!dom || !dom.childNodes) return;
 
         var root = dom.childNodes[0],
             children = root.childNodes,

js/id/id.js

@@ -55,10 +55,12 @@ window.iD = function () {
     }
 
     connection.on('load.context', function loadContext(err, result) {
-        if (altGraph) {
-            _.each(result.data, function(entity) { altGraph.replace(entity); });
-        } else {
-            history.merge(result.data, result.extent);
+        if (!err) {
+            if (altGraph) {
+                _.each(result.data, function(entity) { altGraph.replace(entity); });
+            } else {
+                history.merge(result.data, result.extent);
+            }
         }
     });