When setting the default value for a number, 0 does not display

What the bug is:
When entering a default value for a custom block, most numbers once set show up like below:

A default value of five for a number input:

However, when entering zero in, the " = 0" does not appear:

Although, the zero does appear in the palette:

This behavior is different when using a text input, where the zero is shown in the editor:

How to trigger it:
Create a custom block, and set an input to be a number input, with a default value of zero.

Your browser/computer (eg. Chrome on Mac OS X):
I am using Firefox on a Windows 10 ThinkStation PC.

When you saw this bug (the date or Snap! version are equally helpful):
I have seen this bug today, and in the most recent version of snap (9.2.14).

I can send a project link if this is not reproducible.