[gnome-maps] route: Add error handler

[Marcus Lundblad <mlundblad src gnome org>]

commit 0f6158f1296e7ae5217d81935d0ed21a772877cb
Author: Marcus Lundblad <ml update uu se>
Date:   Mon Apr 16 22:08:12 2018 +0200

    route: Add error handler
    
    Add an error signal and error function to trigger
    an error signal with a message.
    
    Closes #107

 src/route.js | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)
---
diff --git a/src/route.js b/src/route.js
index ec4121f..9777d67 100644
--- a/src/route.js
+++ b/src/route.js
@@ -44,7 +44,8 @@ var TurnPointType = {
 var Route = GObject.registerClass({
     Signals: {
         'update': {},
-        'reset': {}
+        'reset': {},
+        'error': { param_types: [GObject.TYPE_STRING] }
     }
 }, class Route extends GObject.Object {
 
@@ -72,6 +73,10 @@ var Route = GObject.registerClass({
         this.emit('reset');
     }
 
+    error(msg) {
+        this.emit('error', msg);
+    }
+
     createBBox(coordinates) {
         let bbox = new Champlain.BoundingBox();
         coordinates.forEach(function({ latitude, longitude }) {