CRM-14931 - Nicer aja handling of statusBounce errors

That might work in (say) Smarty, but in JS it's an error to access a property on "null" or "undefined" -- eg in Firebug, running:

```
x = {crmForm: null}
x.crmForm.autoClose
```

produces "TypeError: x.crmForm is null". One needs to say:

```
x = {crmForm: null}
x.crmForm && x.crmForm.autoClose
```