async private void comboBox1_SelectedIndexChanged(object sender, EventArgs e) { if (assignment == null) { return; } currentStudent = (Student)studentComboBox.SelectedItem; Feedback fbk = await APIHandler.TeacherGetFeedback(currentStudent, assignment); if (fbk.Exists()) { feedbackTextBox.Text = fbk.feedback; scoreTextBox.Text = fbk.score.ToString(); } else { feedbackTextBox.Text = ""; scoreTextBox.Text = ""; } }