public function merge( SearchIndexField $that ) {
// TODO: which definitions may be compatible?
if ( ( $that instanceof self ) && $this->type === $that->type &&
- $this->flags === $that->flags && $this->type !== self::INDEX_TYPE_NESTED
+ $this->flags === $that->flags && $this->type !== self::INDEX_TYPE_NESTED
) {
return $that;
}