[FORMS] Hidden field in ToggleCompositeField if validation error occurs

[raissanorth]

Affected Version

SilverStripe 4+

Description

When an validation error occurs within the ToggleCompositeField the field is closed by default and the cause of the error is therefore hidden to the user.

I suggest to open the ToggleCompositeField if it contains fields with errors.

Steps to Reproduce

• Create a ToggleCompositeField
• Create a required field within the ToggleCompositeField
• Submit the form without the required field filled

[chillu]

@sachajudd Can we apply the same solution as for tabs here? Or would it just be a matter of auto-expanding the toggle field when there's any validation errors? silverstripe/silverstripe-cms#2081

[sachajudd]

@raissanorth @chillu expanding the toggle field is a good idea see silverstripe/silverstripe-cms#2081 for designs which shows errors in multiple tabs but uses the ToggleCompositeField as an example 🙂

Design can also be found here: https://invis.io/V2FXGW5RSAH