bmx7-info calls returns an invalid JSON structure when no interfaces are configured or no links are established

Certain bmx7-info calls from the web interface (e.g., https://192.168.1.1/cgi-bin/bmx7-info?$info) return an invalid JSON structure with two consecutive commas. This happens when there are no interfaces configured to be used, or when no links can be established to other routers.

Take, for instance, this example, with two commas just before the memory block:

    "info": [{
        "status": {
            "shortId": "EE598CB5",
            etc.
        }
    }, {
        "interfaces": [{
            "dev": "br-lan",
            "state": "UP",
            etc.
        }, {
            "dev": "eth1",
            "state": "UP",
            etc.
        }]
    }, , {
        "memory": {
            "bmx7": "2388 kB"
        }
    }]
}

bmx-routing / bmx7

bmx7-info calls returns an invalid JSON structure when no interfaces are configured or no links are established #38