<s>[INST] import tkinter as tk
from tkinter import messagebox

def calculate():
    num1 = int(entry.get())
    num2 = int(entry2.get())
    result = num1 * num2
    label.config(text="Result: " + str(result))

root = tk.Tk()
root.title("Simple calculator")

frame = tk.Frame(root)
frame.pack()

label = tk.Label(frame, text="Enter a number")
label.pack()

entry = tk.Entry(frame)
entry.pack()

label2 = tk.Label(frame, text="Enter another number")
label2.pack()

entry2 = tk.Entry(frame)
entry2.pack()

button = tk.Button(frame, text="Calculate", command=calculate)
button.pack()

label = tk.Label(frame, text="Result: ")
label.pack()

root.mainloop()

This code is used to create a simple multiplication calculator. How can I add error handling to this code to prevent the program from crashing if the user enters a non-integer value?[/INST]