Prevent undefined options error in background script (#732)
Prevent undefined options error in background script (#732)

```
Error in response to storage.get: TypeError: Cannot read property 'showTomster' of undefined
```
cibernox/ember-inspector,teddyzeenny/ember-inspector,teddyzeenny/ember-extension,sly7-7/ember-inspector,sivakumar-kailasam/ember-inspector,sly7-7/ember-inspector,emberjs/ember-inspector,cibernox/ember-inspector,emberjs/ember-inspector,sivakumar-kailasam/ember-inspector,teddyzeenny/ember-inspector,teddyzeenny/ember-extension