diff --git a/app/attack_log.py b/app/attack_log.py
index c8a78c3..87141c4 100644
--- a/app/attack_log.py
+++ b/app/attack_log.py
@@ -30,7 +30,7 @@ class AttackLog():
         @param verbosity: verbosity setting from 0 to 3 for stdout printing
         """
         self.log: list[dict] = []
-        self.machines: dict = []
+        self.machines: list[dict] = []
         self.verbosity = verbosity
 
         # TODO. As soon as someone wants custom timestamps, make the format variable
@@ -510,6 +510,8 @@ class AttackLog():
         timestamp = self.__get_timestamp__()
         logid = timestamp + "_" + str(randint(1, 100000))
 
+        cframe = currentframe()
+
         data = {"timestamp": timestamp,
                 "timestamp_end": None,
                 "event": "start",
@@ -527,8 +529,8 @@ class AttackLog():
                 "situation_description": kwargs.get("situation_description", None),  # Description for the situation this attack was run in. Set by the plugin or attacker emulation
                 "countermeasure": kwargs.get("countermeasure", None),  # Set by the attack
                 "result": None,
-                "sourcefile": kwargs.get("sourcefile", getsourcefile(currentframe().f_back)),
-                "sourceline": kwargs.get("sourceline", currentframe().f_back.f_lineno)
+                "sourcefile": kwargs.get("sourcefile", getsourcefile(cframe.f_back)),
+                "sourceline": kwargs.get("sourceline", cframe.f_back.f_lineno)
                 }
         self.__add_to_log__(data)
 
@@ -642,7 +644,7 @@ class AttackLog():
 
         return res
 
-    def add_machine_info(self, machine_info):
+    def add_machine_info(self, machine_info: dict):
         """ Adds a dict with machine info. One machine per call of this method """
         self.machines.append(machine_info)
 
diff --git a/app/config.py b/app/config.py
index 6844903..c0bde00 100644
--- a/app/config.py
+++ b/app/config.py
@@ -151,7 +151,7 @@ class ExperimentConfig():
         @param configfile: The configuration file to process
         """
 
-        self.raw_config: Optional[dict] = None
+        self.raw_config: MainConfig = None
         self._targets: list[MachineConfig] = []
         self._attackers: list[MachineConfig] = []
         self.load(configfile)
diff --git a/app/experimentcontrol.py b/app/experimentcontrol.py
index 811db63..92206f4 100644
--- a/app/experimentcontrol.py
+++ b/app/experimentcontrol.py
@@ -8,6 +8,7 @@ import time
 import zipfile
 import shutil
 from datetime import datetime
+from typing import Optional
 
 from app.attack_log import AttackLog
 from app.config import ExperimentConfig
@@ -32,12 +33,14 @@ class Experiment():
         @param verbosity: verbosity level between 0 and 3
         @param caldera_attacks: an optional argument to override caldera attacks in the config file and run just this one caldera attack. A list of caldera ID
         """
-        self.attacker_1 = None
+        self.attacker_1: Optional[Machine] = None
 
         self.experiment_config = ExperimentConfig(configfile)
         self.attack_logger = AttackLog(verbosity)
         self.plugin_manager = PluginManager(self.attack_logger)
         self.__start_attacker()
+        if self.attacker_1 is None:
+            raise ServerError
         caldera_url = "http://" + self.attacker_1.get_ip() + ":8888"
         self.caldera_control = CalderaControl(caldera_url, attack_logger=self.attack_logger, config=self.experiment_config)
         # self.caldera_control = CalderaControl("http://" + self.attacker_1.get_ip() + ":8888", self.attack_logger,