Integer list UI stuck with value zero

Problem/Motivation

The integer list UI gets stuck when having specific settings with a value of zero.

Steps to reproduce

1. Add an integer list field to node type, add the following pairs:
   • abc|0
   • def|1
   • ghi|2
2. Create new node, select the abc|0 pair for the integer list field.
3. Try to edit field settings, e. g. adding a new pair or changing the sort order or just saving the field settings as they are. You will get an error saying that the field value should not be empty.
4. You can only "unstuck" the form by having no nodes with the value 0 selected.

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes

Release notes snippet