bugfix when ref is None

[pcuste1]

What is changing?

Small bugfix to fix an error that occurs when ref == None

Why is this required?

Without this change, we attempt to access self.ref.anchor of None which throws an error. This small fix avoids that issue and manual testing shows that sidecar works appropriately with ref=None

How was this tested

The following code fails to run before this change, and after this change succeeds and opens a healthy sidecar instance as expected.

from sidecar import Sidecar

my_sidecar = Sidecar(anchor="split-right", title="test", ref=None)

[bmorris3]

Thanks Patrick, I'm bummed I missed this.