Import with an unset customField for an access, leads to a failed import

Here is one of my accesses:

{
      "vendorId": "caissedepargne",
      "login": "mySecretLogin",
      "fetchStatus": "INVALID_PASSWORD",
      "customLabel": null,
      "customFields": null,
      "id": 7,
      "fields": [
        {
          "name": "website",
          "value": "www.caisse-epargne.fr"
        },
        {
          "name": "nuser"
        },
        {
          "name": "pincode"
        }
      ]
    },

Some custom fields have no value, this leads to an error in the import (raised by sqllite).