chart.js issue.. plz nn

formatter: function (value, context) {
              var result = value
                .toString()
                .replace(/\B(?=(\d{3})+(?!\d))/g, ",");

              var index = context.dataIndex;
              var fontWeight = index === 0 ? 700 : 500;
              return {
                value: result,
                font: {
                  weight: fontWeight,
                },
              };

              return result;
            },

Chart.js (2.9.4) + Chartjs-datalabels plugin (0.7.0) in use.
Currently, I want to change the label font-weight value of the 0th index to bold.
Label values are output as [object object] values due to the lower return result.

Can I get some advice?