Is there a way to hide the sidenav if it has no content?

here is my current sidenav in application.hbs:

```hbs
{{#paper-sidenav-container}}
{{#paper-sidenav open=leftBarOpen class='md-whiteframe-z2' onToggle=(action (mut leftBarOpen))}}
{{from-elsewhere name='left-side-bar'}}
{{/paper-sidenav}}
...
```
what I'd like to be able to do, is if the content of from-elsewhere is empty, don't have the sidebar.
I'm swapping out the sidebar via `to-elsewhere` depending on the route.

For large pages without a sidebar, the blank space on the left looks kinda weird, ya know?
for mobile sizes, since it's at least 'hidden' -- it doesn't look so bad. :-)

But also, I wonder if there'd be a way to optionally make it mobile only?

Maybe the solution is to wrap the from-elsewhere in:

```hbs

where, I just also set `sidenavWrapperClass` depending on the route, and have it always revert to `''` or something.

idk.

how would you go about this?