I need help because I can't resolve this error even putting sidetiltle

[pradofelipe]

import 'package:flutter/material.dart';
import 'package:fl_chart/fl_chart.dart';

class WeightChart extends StatefulWidget {
@OverRide
_WeightChartState createState() => _WeightChartState();
}

class _WeightChartState extends State {
List<Map<String, dynamic>>? chartData = [
{"measured_at": "2022-01-01", "weight": 70.0},
{"measured_at": "2022-02-01", "weight": 72.0},
{"measured_at": "2022-03-01", "weight": 71.5},
{"measured_at": "2022-04-01", "weight": 73.0},
{"measured_at": "2022-05-01", "weight": 72.5},
{"measured_at": "2022-06-01", "weight": 72.8},
{"measured_at": "2022-07-01", "weight": 74.0},
]; // Lista para armazenar os dados do gráfico

@OverRide
Widget build(BuildContext context) {
return LineChart(
LineChartData(
minX: 0,
maxX: (chartData!.length - 1).toDouble(), // Define o intervalo no eixo X

    // Configuração do gráfico...
    titlesData: FlTitlesData(
      // Define os rótulos para o eixo X
      bottomTitles: AxisTitles(
        showTitles: true,
        interval: 1,
        getTitles: (value) {
          if (value.toInt() < chartData!.length) {
            return chartData![value.toInt()]["measured_at"]
                .toString()
                .substring(5, 7); // Apenas o mês
          }
          return '';
        },
      ),
      // Define os rótulos para o eixo Y
      leftTitles: AxisTitles(
        showTitles: true,
        interval: 1,
        getTitles: (value) {
          return value.toInt().toString();
        },
      ),
    ),
    gridData: FlGridData(show: true),
    borderData: FlBorderData(show: true),
    lineBarsData: [
      LineChartBarData(
        spots: List.generate(
          chartData!.length,
          (index) {
            // Cria um ponto no gráfico para cada medida de peso
            final weight = double.parse(chartData![index]["weight"].toString());
            return FlSpot(index.toDouble(), weight);
          },
        ),
        isCurved: true,
        colors: [Colors.blue],
        barWidth: 4,
        isStrokeCapRound: true,
        belowBarData: BarAreaData(show: false),
      ),
    ],
  ),
);

}
}

[imaNNeo]

Please provide more information. And a reproducible code (a main.dart file content)