Edit Custom Fields : Erroneous form validation error occurs when saving an existing custom field - "Option Type is a required field"

This problem occurs when there are not option groups linked to custom fields (yet). So to recreate - start with a DB that does NOT have sample data loaded. Then create a custom field type = Yes / No. Save the field, then go to edit it and try to save it again. You'll get the form validation error on the option_type field.

NOTE: if you create a select, radio or checkbox field first - you won't see this bug.

The cause of this is that the code goes to this condtion (Custom/Field.php):

if ( empty( $optionGroups ) ) {
$optionTypes = array( '1' => ts( 'Create a new set of options' ) );
$extra = array( 'onclick' => "showOptionSelect();");
$element =& $this->addRadio( 'option_type',
ts('Option Type'),
$optionTypes,
$extra,
'<br/>', true
);
$element->freeze( );

... and if you do a view source - the option_type field actually doesn't exist in the source (it would be hidden and frozen in any case) .

I'm not sure what the right fix is? Maybe we need to make the presence of that "required" field conditional when in UPDATE mode - not add it to the form object when the HTML type is not checkbox, radio or mult-select.