Notice: Undefined index: vocabulary in taxonomy_field_views_data() (line 415 of /sites/all/modules/views/modules/taxonomy.views.

I couldn't find this error in the issue queue, but I'm receiving it very often: after a cache flush, when visiting structure>views, after saving a view, after enabling modules, and many other occasions. Refreshing the page temporarily rids the error, and I've noticed this with all roles.

The error:
Notice: Undefined index: vocabulary in taxonomy_field_views_data() (line 415 of <path>/sites/all/modules/views/modules/taxonomy.views.inc).

taxonomy.views.inc line 415:

$data[$table_name][$field_name]['filter']['vocabulary'] = $field['settings']['allowed_values'][0]['vocabulary'];

taxonomy.views.inc conflicting function (I commented // HERE after it):

/**
 * Implements hook_field_views_data().
 *
 * Views integration for taxonomy_term_reference fields. Adds a term relationship to the default
 * field data.
 *
 * @see field_views_field_default_views_data()
 */
function taxonomy_field_views_data($field) {
  $data = field_views_field_default_views_data($field);
  foreach ($data as $table_name => $table_data) {
    foreach ($table_data as $field_name => $field_data) {
      if (isset($field_data['filter'])) {
        $data[$table_name][$field_name]['filter']['handler'] = 'views_handler_filter_term_node_tid';
        $data[$table_name][$field_name]['filter']['vocabulary'] = $field['settings']['allowed_values'][0]['vocabulary']; // HERE
      }
    }

    // Add the relationship only on the tid field.
    $data[$table_name][$field['field_name'] . '_tid']['relationship'] = array(
      'handler' => 'views_handler_relationship',
      'base' => 'taxonomy_term_data',
      'base field' => 'tid',
      'label' => t('term from !field_name', array('!field_name' => $field['field_name'])),
    );

  }

  return $data;
}