Set default value to custom field of type single-choice IP_1.5.4

We added a custom field and set an number of values. The problem is that none is set as default in the quote input leading to a fault when creating the PDF.

Is it possible to not only specify a custom field and its possible values as done now but also set one of the provided values as default to avoid empty field issues when creating the PDF?

I would prefer setting a default for the field to fixing the PDF template with a test if possible.

Thanks in advance

Using the first item from the list of values would make my day (one can always add a fake first item called ‘none’ if necessary)
How / where can I set the default value to first item instead of current ‘none’?