Zend certified PHP/Magento developer

Magento 2 extension submission to the marketplace was failed

"command": "composerConfigRepository0",
                        "output": [
                            "Finished with the '0' exit code."
                        ]

I made my own plugin and tried putting it on the marketplace. But it didn’t pass the technical review and there’s an error in the first line of the report JSON. Can you help me fix it?