[BUG] Empty map keys are not handled correctly

[nieomylnieja]

Describe the bug
Property errors for map keys validation does not handle empty strings. Instead of a path like metadata.labels."" we get metadata.labels.

To Reproduce
Set map key to an empty string, run validation. The result is a property path without the empty string key element.

Expected behavior
The result should be a valid YAMLPath pointing at the empty key.

System details (please complete the following information)

• govy version v0.1.1