title: simple_form nested form select wrapper always displaying error class
body: <p>I have a nested form with simple_form and simple_fields_for.</p>
  
  <p>I have a select in a table using:</p>
  
  <pre><code>item.input_field :budget_code_item_id, collection: @budget_code.budget_code_items.order(code: :asc), label_method: :select_label, value_method: :id,label: false, include_blank: 'Select a budget code...', class: "text-xs select form-control"
  </code></pre>
  
  <p>The problem is that it renders this:</p>
  
  <pre><code>&lt;select class=" error select required form-control text-xs select form-control" label="false" include_blank="Select a budget code..." name="budget[budget_items_attributes][0][budget_code_item_id]" id="budget_budget_items_attributes_0_budget_code_item_id"&gt;
     &lt;option value=""&gt;Select a budget code...&lt;/option&gt;
  &lt;/select&gt;
  </code></pre>
  
  <p>The error code is being applied to the selects all the time even when the fields are valid. The other input text fields are fine - just the selects.</p>
  
  <p>I can't figure out why it's doing this - the error class should only apply when the field is invalid on form submission.</p>