赋值前引用的Tkinter错误局部变量

Question

我正在尝试制作一个程序，一旦勾选了勾选框，电子邮件的字段就会出现，但当取消勾选时，当您按下更新时，字段就会消失

但我不断得到：

emailLabel.destroy()

UnboundLocalError: local variable 'emailLabel' referenced before assignment

有什么建议吗？下面是我的代码：

#so when you tick the box, the value is 1 so this checks for that and sets a equal to 1 
#if the box isnt ticked then it checks a and if it is equal to 1 then it
#deletes the fields for the email and code.

#PLEASE HELP. Error is in this bit

def update(var1):
    global signupas
    global a
    print(a)
    checklist = var1.get()
    print(checklist)

    if checklist == 1:
        a= 1
        if a == checklist:

            # // but it's referenced here:
            global email
            emailLabel = Label(signupas, text="Email")
            emailLabel.grid(row=3, column=0)
            email = StringVar()
            emailEntry = Entry(signupas, textvariable=email)
            emailEntry.grid(row=3, column=1)
            codeLabel = Label(signupas, text="code")
            codeLabel.grid(row=4, column=0)
            code = StringVar()
            codeEntry = Entry(signupas, textvariable=email)
            codeEntry.grid(row=4, column=1)
    #its on about this bit: 
    if a == 1 and checklist == 0:
        emailLabel.destroy()
        codeLabel.destroy()
    
    signupas.mainloop()

#//this gets the information for the update as it checks for the check box
#//error isn't here but above so don't worry about signup().

def signup():
    global signupas
    signupas = tk.Toplevel()
    signupas.geometry('300x200')  
    tkWindow.title("database program")
    usernameLabel = Label(signupas, text="Username").grid(row=0, column=0)
    username = StringVar()
    usernameEntry = Entry(signupas, textvariable=username).grid(row=0, column=1)  
    passwordLabel = Label(signupas,text="Password").grid(row=1, column=0)  
    password = StringVar()
    passwordEntry = Entry(signupas, textvariable=password, show='*').grid(row=1, column=1)
    var1 = IntVar()
    Checkbutton(signupas, text="2step verification", variable=var1).grid(row=2)                                                                            
    SignUp = partial(checkuser_email, username, password, var1)
    updates = partial(update, var1)
    updateButton = Button(signupas, text="Update", command=updates).grid(row=5, column=2)
    signupButton = Button(signupas, text="SignUp", command=SignUp).grid(row=5, column=1)
    signupas.mainloop()

提前感谢：）