Fatal error prevents deletion of options from custom fields

When you attempt to delete an option from a custom field that uses an option group (e.g. a Select, Radio, Checkbox or Multi-Select field) you get a fatal error and the option is not deleted.

This error occurs in 4.4.0 and can be reproduced on the 4.4.1 demo site.

The error occurs when using the web UI but not the API.