Bugfix: Allow breadcrumb for variant root items

[madsrasmussen]

Description

We currently get a js error in the console when creating a document in the root. This is caused because the unique is null and we throw an error when falsy. This fix changes the code to only check for undefined.

How to test

• Create a document in the root. You will see the error in the console.
• After the fix is applied the error is gone.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Chore (minor updates related to the tooling or maintenance of the repository, does not impact compiled assets)