fix(ng2.uiView): Dispose prev comp on empty viewconfig

Author: christopherthielen

src/ng2/uiView.ts

@@ -31,13 +31,13 @@ const getProviders = (injector) => {
     }`
   ],
   template: `<div #content></div>`,
-  // debugtemplate: `
+  // template: `
   // <div style="padding: 1em; border: 1px solid lightgrey;">
   //
   //   <div #content style="color: lightgrey; font-size: smaller;">
   //     <div>ui-view #{{uiViewData.id}} created by '{{ parentContext.name || "(root)" }}' state</div>
   //     <div>name: (absolute) '{{uiViewData.fqn}}' (contextual) '{{uiViewData.name}}@{{parentContext.name}}' </div>
-  //     <div>currently filled by: '{{(uiViewData.config && uiViewData.config.context) || 'empty...'}}'</div>
+  //     <div>currently filled by: '{{(uiViewData.config && uiViewData.config.viewDecl.$context) || 'empty...'}}'</div>
   //   </div>
   //
   // </div>`
@@ -90,7 +90,10 @@ export class UiView {
   }
 
   viewConfigUpdated(config: ViewConfig) {
-    if (!config) return; // TODO do something smarter
+    if (!config) {
+      return this.disposeLast();
+    }
+
     let {uiViewData, injector, dcl, elementRef} = this;
     let viewDecl = <Ng2ViewDeclaration> config.viewDecl;