Undefined index: name under System Upgrade

[prathers]

Just wanted to do an upgrade from v2.1.7 to 2.1.8 through System Upgrade in Admin and got an error Undefined index: name during the initial check.
I found out that the composer config repositories.tinify vcs https://github.com/tinify/magento2-plugin result in a composer.json like this:

"repositories": {
      "0": {
            "type": "composer",
            "url": "https://repo.magento.com/"
        },
        "tinify": {
            "type": "vcs",
            "url": "https://github.com/tinify/magento2-plugin"
        }
    },

If I remove the tinify and redo my composer.json:

"repositories": [
        {
            "type": "composer",
            "url": "https://repo.magento.com/"
        }
    ],

..it works again.
Any idea?