function _markValidSubpaths(doc, path) {
  if (!doc.$__.validationError) {
    return;
  }

  const keys = Object.keys(doc.$__.validationError.errors);
  for (const key of keys) {
    if (key.startsWith(path + '.')) {
      delete doc.$__.validationError.errors[key];
    }
  }
  if (Object.keys(doc.$__.validationError.errors).length === 0) {
    doc.$__.validationError = null;
  }
}
Marks a path as valid, removing existing validation errors.

@param {String} path the field to mark as valid
@api public
@memberOf Document
@instance
@method $markValid