Spacer shows null in the dimension tooltip

[draganescu]

Description

When dragging the spacer block to resize it horizontally, when there is no way to resize it vertically the tooltip informing of the achieved result is showing a "null" string for vertical size.

Step-by-step reproduction instructions

1. Edit a header template part in isolation
2. Add a navigation block, if one does not exist
3. In the navigation block add a spacer
4. Drag to resize the spacer horizontally
5. Notice the bug

Screenshots, screen recording, code snippet

Environment info

No response

Please confirm that you have searched existing issues in the repo.

Yes

Please confirm that you have tested with all plugins deactivated except Gutenberg.

Yes

[richtabor]

when there is no way to resize it vertically

Do you know why this is a limitation? Seems odd that there's an arbitrary height applied (24px) when used within a Row block.

[draganescu]

No, I have not looked into this.