fix bug with null dep
fix bug with null dep



Former-commit-id: 94984a658c9b341c2bf00f37c0dca2c3c6b526cb
charybdeBE/Cytomine-core,charybdeBE/Cytomine-core,cytomine/Cytomine-core,cytomine/Cytomine-core,charybdeBE/Cytomine-core,charybdeBE/Cytomine-core,charybdeBE/Cytomine-core,charybdeBE/Cytomine-core,cytomine/Cytomine-core,charybdeBE/Cytomine-core,charybdeBE/Cytomine-core,cytomine/Cytomine-core,charybdeBE/Cytomine-core,cytomine/Cytomine-core,charybdeBE/Cytomine-core,cytomine/Cytomine-core