[Admin UI] Optional custom fields of type int get populated with 0 instead of null

[seminarian]

Describe the bug
Optional custom fields of type int get populated with 0 instead of null

To Reproduce
Steps to reproduce the behavior:

    config.customFields.Product.push({
      name: 'numberOfPhotos',
      label: [
        {
          languageCode: LanguageCode.en,
          value: 'Number of photos',
        },
      ],
      type: 'int',
    });

It shows up in the Admin UI but when creating a new product and not filling in this specific custom field the Admin UI does send it with value 0
On the edit product screen the value 0 is indeed shown while actually it should just be empty.

Expected behavior
If an optional custom field of type int is not filled in null should be sent to server

Environment (please complete the following information):

• @vendure/core version: 2.0.3
• Nodejs version: v16.19.0
• Database (mysql/postgres etc): postgres