fix the bug that missing map-properties affects the bahavior of map-feature with link

Author: yhy0217

src/mapml/features/geometry.js

@@ -14,14 +14,14 @@ export var Geometry = L.FeatureGroup.extend({
     L.LayerGroup.prototype.initialize.call(this, layers, options);
     this._featureEl = this.options.mapmlFeature;
 
+    let firstLayer = layers[Object.keys(layers)[0]];
+    if (layers.length === 1 && firstLayer.options.link)
+      this.options.link = firstLayer.options.link;
     if (
       (this.options.onEachFeature && this.options.properties) ||
       this.options.link
     ) {
       L.DomUtil.addClass(this.options.group, 'leaflet-interactive');
-      let firstLayer = layers[Object.keys(layers)[0]];
-      if (layers.length === 1 && firstLayer.options.link)
-        this.options.link = firstLayer.options.link;
       if (this.options.link) {
         M.Path.prototype.attachLinkHandler.call(
           this,