Generated PHP has strange if-statements

Example from https://github.com/owncloud/libre-graph-api-php/blob/main/lib/Api/TagsApi.php getTagsWithHttpInfo()

            switch($statusCode) {
            
                case 200:
                    if ('\OpenAPI\Client\Model\CollectionOfTags' === '\SplFileObject') {
                        $content = $response->getBody(); //stream goes to serializer
                    } else {
                        $content = (string) $response->getBody();
                        if ('\OpenAPI\Client\Model\CollectionOfTags' !== 'string') {
                            $content = json_decode($content);
                        }
                    }

                    return [
                        ObjectSerializer::deserialize($content, '\OpenAPI\Client\Model\CollectionOfTags', []),
                        $response->getStatusCode(),
                        $response->getHeaders()
                    ];
            
            
                default:
                    if ('\OpenAPI\Client\Model\OdataError' === '\SplFileObject') {
                        $content = $response->getBody(); //stream goes to serializer
                    } else {
                        $content = (string) $response->getBody();
                        if ('\OpenAPI\Client\Model\OdataError' !== 'string') {
                            $content = json_decode($content);
                        }
                    }

                    return [
                        ObjectSerializer::deserialize($content, '\OpenAPI\Client\Model\OdataError', []),
                        $response->getStatusCode(),
                        $response->getHeaders()
                    ];
            
            }

            $returnType = '\OpenAPI\Client\Model\CollectionOfTags';
            if ($returnType === '\SplFileObject') {
                $content = $response->getBody(); //stream goes to serializer
            } else {
                $content = (string) $response->getBody();
                if ($returnType !== 'string') {
                    $content = json_decode($content);
                }
            }

            return [
                ObjectSerializer::deserialize($content, $returnType, []),
                $response->getStatusCode(),
                $response->getHeaders()
            ];

Note: the first PHP was generated by https://github.com/owncloud/libre-graph-api/pull/113

The example is in lib/Api/TagsApi.php, in getTagsWithHttpInfo(); start by comparing this generated method with the generation inputs or templates used by the PHP client. Determine the intended handling for CollectionOfTags, OdataError, and the return type, then verify that regenerated output no longer contains the reported conditions.