Ошибка с plainTextEdit

import pickle
from PyQt5 import uic
from PyQt5.QtWidgets import QApplication
from PyQt5.QtWidgets import QApplication, QWidget, QPlainTextEdit, QVBoxLayout
import math
 
Form, Window = uic.loadUiType("kale1.ui")
 
app = QApplication([])
window = Window()
form = Form()
form.setupUi(window)
window.show()
 
 
def on_click():
    global calc_date, description, start_date
    start_date = now_date
    calc_date = form.calendarWidget.selectedDate()
    description = form.plainTextEdit.toPlainText()
    # print(form.plainTextEdit.toPlainText())
    # print(form.dateEdit.dateTime().toString('dd-MM-yyyy'))
    print("Clicked!!!")
    save_to_file()
    # print(form.calend
 
 
def save_to_file():
    global start_date, calc_date, description
    #start_date = QDate(2020, 12, 1)
    data_to_save = {"start": start_date, "end": calc_date, "desc": description}
    file1 = open("fail.txt", "wb")
    pickle.dump(data_to_save, file1)
    file1.close()
 
 
def on_click_calendar():
    global start_date, calc_date
    #print(form.calendarWidget.selectedDate().toString('dd-MM-yyyy'))
    form.dateEdit.setDate(form.calendarWidget.selectedDate())
    calc_date = form.calendarWidget.selectedDate()
    delta_days = start_date.daysTo(calc_date)
    a = [1]
    a1 = [2, 3, 4]
    a2 = [5, 6, 7, 8, 9, 0]
    if abs(delta_days)%10 in a:
        if delta_days >= 0:
            form.label_2.setText("До наступления события осталось: %s день" % delta_days)
        else:
            form.label_2.setText("С события прошел: %s день" % -delta_days)
    if abs(delta_days)%10 in a1:
        if delta_days >= 0:
            form.label_2.setText("До наступления события осталось: %s дня" % delta_days)
        else:
            form.label_2.setText("С события прошло: %s дня" % -delta_days)
    if abs(delta_days)%10 in a2:
        if delta_days >= 0:
            form.label_2.setText("До наступления события осталось: %s дней" % delta_days)
        else:
            form.label_2.setText("С события прошло: %s дней" % -delta_days)
 
 
 
def on_dateedit_change():
    global start_date, calc_date
    #print(form.dateEdit.dateTime().toString('dd-MM-yyyy'))
    form.calendarWidget.setSelectedDate(form.dateEdit.date())
    calc_date = form.dateEdit.date()
    delta_days = start_date.daysTo(calc_date)
    if delta_days >= 0:
        form.label_2.setText("До наступления события осталось: %s дней" % delta_days)
    else:
        form.label_2.setText("С события прошло: %s дней" % -delta_days)
 
 
form.pushButton.clicked.connect(on_click)
form.calendarWidget.clicked.connect(on_click_calendar)
form.dateEdit.dateChanged.connect(on_dateedit_change)
 
 
form.pushButton.clicked.connect(on_click)
start_date = form.calendarWidget.selectedDate()
description = form.plainTextEdit.toPlainText()
form.label.setText("Трекер события от %s" % start_date.toString('dd-MM-yyyy'))
on_click_calendar()
 
#
 
app.exec_()