How can javascript extract specified key value from json blob with many nested values?

I have an https query which returns a json blob in the following format:

{
"metric_data": {
    "from": "2021-12-09T01:25:32+00:00",
    "to": "2021-12-09T01:55:32+00:00",
    "metrics_not_found": [],
    "metrics_found": [
        "Mobile/Crash/All"
    ],
    "metrics": [
        {
            "name": "Mobile/Crash/All",
            "timeslices": [
                {
                    "from": "2021-12-09T01:24:00+00:00",
                    "to": "2021-12-09T01:54:00+00:00",
                    "values": {
                        "call_count": 5
                    }
                }
            ]
        }
    ]
}

}

I want to find and extract the value for call_count. What is the best way to do that with Javascript? The following code will actually print out all the json values, including the call_count but all my efforts to just grab the value for call_count are failing.

var json = `{
"metric_data": {
    "from": "2021-12-09T01:25:32+00:00",
    "to": "2021-12-09T01:55:32+00:00",
    "metrics_not_found": [],
    "metrics_found": [
        "Mobile/Crash/All"
    ],
    "metrics": [
        {
            "name": "Mobile/Crash/All",
            "timeslices": [
                {
                    "from": "2021-12-09T01:24:00+00:00",
                    "to": "2021-12-09T01:54:00+00:00",
                    "values": {
                        "call_count": 5
                    }
                }
            ]
        }
    ]
}
}`;
    
    // Convert a JSON object to a Javascript object
var obj = JSON.parse(json);

// This function prints nested values
function printValues(obj) {
    for(var k in obj) {
        if(obj[k] instanceof Object) {
            printValues(obj[k]);
        } else {
            document.write(obj[k] + "<br>");
        };
    }
};

// Printing all the values from the resulting object
printValues(obj);

document.write("<hr>");
    
    // This is where I fail as I try to print a single value.
    document.write(obj["metrics"]["call_count"] + "<br>");

Any feedback would be much appreciated!