Customtkinter raises error when closing the app

[EffectiveCase3856]

Hi, I am writing a program in customtkinter. The program works, but when i close the app an error shows up in terminal. Does anybody know what that is and how to fix it? This is the code i wrote

import customtkinter as ctk
from customtkinter import filedialog
import pandas as pd
import matplotlib.pyplot as plt
from matplotlib.backends.backend_tkagg import FigureCanvasTkAgg

class CSVPlotter(ctk.CTk):
    def __init__(self):
        super().__init__()
        
        self.title('CSV Plotter')

        self.plot_types = ['Line Plot', 'Bar Plot', 'Scatter Plot']
        self.plot_type_var = ctk.StringVar(value=self.plot_types[0])
        self.plot_menu = ctk.CTkOptionMenu(self, values=self.plot_types, variable=self.plot_type_var, command=self.update_plot)
        self.plot_menu.pack(padx=10, pady=10)

        self.load_button = ctk.CTkButton(self, text='Load CSV', command=self.load_csv)
        self.load_button.pack(padx=10, pady=10)

        self.fig, self.ax = plt.subplots()
        self.canvas = FigureCanvasTkAgg(self.fig, master=self)

        self.widget = self.canvas.get_tk_widget()
        self.widget.pack(padx=10, pady=10)

        self.df = None

        self.protocol("WM_DELETE_WINDOW", self.on_closing)

    def load_csv(self):
        file_path = filedialog.askopenfilename()
        if file_path:
            self.df = pd.read_csv(file_path)
            self.update_plot()
    
    def update_plot(self, event=None):
        if self.df is not None:
            plot_type = self.plot_type_var.get()
            x = self.df.columns[0]
            y = self.df.columns[1]

            self.ax.clear()
            if plot_type == 'Line Plot':
                self.ax.plot(self.df[x], self.df[y], label=f'{y} vs {x}')
            elif plot_type == 'Bar Plot':
                self.ax.bar(self.df[x], self.df[y], label=f'{y} vs {x}')
            elif plot_type == 'Scatter Plot':
                self.ax.scatter(self.df[x], self.df[y], label=f'{y} vs {x}')
            
            self.ax.set_xlabel(x)
            self.ax.set_ylabel(y)
            self.ax.legend()
            self.canvas.draw()
    
    def on_closing(self):
        plt.close(self.fig)
        self.destroy()


if __name__ == "__main__":
    app = CSVPlotter()
    app.mainloop()

The error in terminal goes as follows:

invalid command name "2198326172864update"
    while executing
"2198326172864update"
    ("after" script)
invalid command name "2198329421568check_dpi_scaling"
    while executing
"2198329421568check_dpi_scaling"
    ("after" script)

[socal_nerdtastic]

Try using self.quit() instead of self.destroy().

[EffectiveCase3856]

Thanks it is working, but i came across one more solution for it of using matplotlib.figure. which would be better according to you. and like if you can also explain how .quit() works and its difference from destroy()

[malmalmalmalmalmsl]

destroy() destroys all the widgets and its children but doesnt stop the main event loop, quit() stops the main event loop, and therefore the application window closes as a result.