"None" as a selectable option for a multi select

While it's not a fix, I find that adding this configuration option makes it easy for the user to remove the "-None-" value:

{
    "removeItemButton": true
}

NOTE: If you leave the "-None-" option in place and choose another option (assuming allow multiple values), the "-None-" value won't get saved to the entity. Next time you edit the entity the "-None-" option won't show.

Here's another workaround. It doesn't seem to break anything. The result is a "Search..." placeholder in the empty box if there is no value, and a "Search..." placeholder at the end of any existing choices if there are any.

1) Set your Choices configuration as follows:

{
    "removeItemButton": true,
    "placeholder": true,
    "placeholderValue": "Search..."
}

2) Use hook_form_alter or hook_form_FORM_ID_alter to unset the _none option:

/**
 * Implements hook_form_alter().
 */
function mymodule_form_alter(&$form, FormStateInterface $form_state, $form_id) {
  if ($form_id == 'node_mycontenttype_edit_form') {
    unset($form['field_languages_spoken']['widget']['#options']['_none']);
  }
}

Thanks @agileadam, I'm thinking about if we should add a logic for this in the module. That would have to happen in JS, as that's how the widgets are applied (to be universal, not specific to certain forms).

If we add anything, I'd vote to do it by a setting so this custom functionality can be turned off.

Thanks for sharing your workarounds!