diff --git a/src/unisync/synchroniser.py b/src/unisync/synchroniser.py
index 6f3e911..b56a8c9 100644
--- a/src/unisync/synchroniser.py
+++ b/src/unisync/synchroniser.py
@@ -10,7 +10,6 @@ the remote.
 import subprocess
 import os
 import sys
-import time
 import logging
 
 from pathlib import Path
@@ -50,26 +49,27 @@ class Synchroniser:
     """
 
     def __init__(self, remote:str, local:str, user:str, ip:str, port:int=22,
-                 args_bool:list=[], args_value:dict={}, ssh_settings:dict={},
-                 backup:BackupConfig | None = None
+                 args_bool:list[str] | None = None, args_value:dict[str, str] | None = None,
+                 ssh_settings:dict[str, str] | None = None, backup:BackupConfig | None = None
                  ):
         """Initialises an instance of Synchroniser.
         """
         self.remote_dir:str = remote
         self.local:str = local
-        self.args_bool:list[str] = args_bool 
-        self.args_value:dict[str, str] = args_value 
-        self.ssh_settings:dict[str, str] = dict()
+        self.args_bool:list[str] = args_bool if args_bool is not None else []
+        self.args_value:dict[str, str] = args_value if args_value is not None else {}
+        self.ssh_settings:dict[str, str] = ssh_settings if ssh_settings is not None else {}
         self.remote_user:str = user
-        self.remote_ip:str = ip 
+        self.remote_ip:str = ip
         self.remote_port:int = port
-        self.files_extra:list = list()
-        self.links_extra:list = list()
+        self.files_extra:list = []
+        self.links_extra:list = []
+        self.control_path:str = ""
 
-        if(backup != None and backup.enabled):
+        if backup is not None and backup.enabled:
             backup = cast(BackupConfig, backup)
             self.files_extra.append("-backup")
-            if(backup.selection != ""):
+            if backup.selection != "":
                 self.files_extra.append(backup.selection)
             else:
                 self.files_extra.append("Name *")
@@ -91,8 +91,10 @@ class Synchroniser:
                 "-ignore",
                 f"Name {backup.backupprefix[:-1]}"
                 ])
-    
-    def create_ssh_master_connection(self, control_path:str="~/.ssh/control_%C", connection_timeout:int=60) -> None:
+
+    def create_ssh_master_connection(self, control_path:str="~/.ssh/control_%C",
+                                     connection_timeout:int=60
+                                     ) -> None:
         """Creates an ssh master connection.
 
         It is used so the user only has to authenticate once to the remote server.
@@ -322,5 +324,5 @@ class Synchroniser:
                 f"{self.remote_user}@{self.remote_ip}:{self.remote_dir}/.data",
                 str(path_to_mount)
                 ]
-        completed_process = subprocess.run(command)
+        completed_process = subprocess.run(command, check=True)
         completed_process.check_returncode()