Offset argument contained a NaN value flutter fl chart line chart

Question

my purpose is to get a data set to plot a line chart using fl chart package in flutter. But i am getting a exception called offset contain nan value.But the offset are in double value.

for (var i = 0; i < tempDataSet.length; i++) { widget.dataset.add(FlSpot(tempDataSet[i].date.day.toDouble(), tempDataSet[i].amount.toDouble())); print(tempDataSet[i].date.day.toDouble().runtimeType); print(tempDataSet[i].amount.toDouble().runtimeType); }