Magento 2: FastSimpleImport Integrity constraint violation

Question

I'm trying to import some products with Firegento FastSimpleImport

https://github.com/firegento/FireGento_FastSimpleImport2 https://github.com/firegento/FireGento_FastSimpleImport2_Demo

When I run the demo for configurable products the first Import works.

The second time i run the Demo i get an error:

/var/www/src/htdocs$ bin/magento fastsimpleimportdemo:products:importconfigurable

Import started

SQLSTATE[23000]: Integrity constraint violation: 1451 Cannot delete or update a parent row: a foreign key constraint fails (database.catalog_product_super_attribute_label, CONSTRAINT FK_309442281DF7784210ED82B2CC51E5D5 FOREIGN KEY (product_super_attribute_id) REFERENCES catalog_product_super_attribute (p), query was: INSERT INTO catalog_product_super_attribute (product_super_attribute_id,position,product_id,attribute_id) VALUES (?, ?, ?, ?) ON DUPLICATE KEY UPDATE product_super_attribute_id = VALUES(product_super_attribute_id), position = VALUES(position), product_id = VALUES(product_id), attribute_id = VALUES(attribute_id`)

1: Begin data validation

2: The validation is complete.

3: Checked rows: 3, checked entities: 3, invalid rows: 0, total errors: 0

4: Import data validation is complete. Import finished. Elapsed time: 3.45s

I tried it with an different Shop and it worked the second time. Does somebody know how to fix this problem?