Extending blueprints in "Kirby Builder" blocks

I just noticed that when i try to reuse a blueprint in the “site/blueprint/fields” folder inside a Kirby Builder blueprint snippet, like this:

margin: fields/margin

I´m getting this error:

    array_merge(): Expected parameter 2 to be an array, string given

When I reference the snippet like this

    extends: fields/margin

everything works as expected. Why is that?

Because the builder fields expects an array here. That’s specific to the builder field (works as expected in a structure field) and to find out why that’s the case, we’d have look into the source code or ask the developer of the plugin.

Thanks a lot.