颤振-无效值：不在包含范围0内。。2: 3

我收到此错误“无效值：不在包含范围0内…”。。2:3'试图在文本字段中将现有答案显示为提示文本

TextField(
                    onChanged: (String ansr) {
                      answers[question] = ansr;
                    },
                    onSubmitted: (String ansr) {
                      _write(answers);
                    },
                    controller: myController,
                    decoration: InputDecoration(
                      enabledBorder: OutlineInputBorder(
                        borderRadius: BorderRadius.circular(20),
                        borderSide: BorderSide(
                          color: Color.fromARGB(255, 128, 124, 124),
                        ),
                      ),
                      focusedBorder: OutlineInputBorder(
                        borderRadius: BorderRadius.circular(20),
                        borderSide: BorderSide(
                          color: Color.fromARGB(255, 128, 124, 124),
                        ),
                      ),
                      border: OutlineInputBorder(
                        borderRadius: BorderRadius.circular(20),
                        borderSide: BorderSide(
                          color: Color.fromARGB(255, 128, 124, 124),
                        ),
                      ),
                      hintText: data[index].answer.isEmpty ? "Write something" :  data[index].answer
                    ),
                  ),