v9 Starter Kit Macro Partial "FeaturedProduct" throws error: Value cannot be null. (Parameter 'source')

[idseefeld]

Which exact Umbraco version are you using? For example: 9.0.1 - don't just write v9
9.4.2

Bug summary
The macro "Select Featured Products" throws an error:

Value cannot be null. (Parameter 'source')

Specifics
No response

Steps to reproduce
I am using a fresh install of v9.4.2.
I have tried to insert "Select Featured Products" macro on the Homepage and got the error after selecting a product and submitting.

Expected result / actual result
After changing line 17 of Settings > Partial View Macro Files > FeaturedProducts.cshtml to:

var selection = Model.MacroParameters.FirstOrDefault(p => p.Key == "product").Value?.ToString().Split(',');
the macro works. And I could also update the product parameter of Settings > Macros > Select Featured Products from Content Picker to Multiple Content Picker.