added null check to prevent error from element-resize-detector in the following tick

Author: Tino Groteloh

dist/vue-grid-layout.js

@@ -1,6 +1,6 @@
 {
   "name": "vue-grid-layout",
-  "version": "1.1.0",
+  "version": "1.1.1",
   "description": "A draggable and resizable grid layout, as a Vue component.",
   "keywords": [
     "grid",

dist/vue-grid-layout.js.map

@@ -101,6 +101,9 @@
 
                 self.updateHeight();
                 self.$nextTick(function () {
+                    if(!self.$els.item)
+                        return;
+
                     var erd = elementResizeDetectorMaker({
                         strategy: "scroll" //<- For ultra performance.
                     });
@@ -119,6 +122,8 @@
 
                 self.updateHeight();
                 self.$nextTick(function () {
+                    if(!self.$els.item)
+                        return;
                     var erd = elementResizeDetectorMaker({
                         strategy: "scroll" //<- For ultra performance.
                     });