当尝试从tkinter列表框中的光标选择返回值时，出现‘错误列表框索引’错误

import tkinter as tk

def get_selected_value():
    index = listbox.curselection()
    if index:
        value = listbox.get(index[0])
        return value
    else:
        return None

root = tk.Tk()

listbox = tk.Listbox(root)
listbox.pack()

listbox.insert(0, "Item 1")
listbox.insert(1, "Item 2")
listbox.insert(2, "Item 3")

selected_value = get_selected_value()
if selected_value:
    print("Selected value:", selected_value)
else:
    print("No value selected")

root.mainloop()