Use error logging for invalid absence configuration

Author: felixschndr

source/abscence_handler.py

@@ -18,8 +18,9 @@ def check_for_current_absence(self) -> bool:
             absence_input = EnvironmentVariableGetter.get("ABSENCE_TIMEFRAME", "")
             return self._check_for_current_absence(absence_input)
         except ValueError:
-            self.log.warning(
-                f'Improperly configured: "{absence_input}" is not a valid configuration! Read the README for instructions.',
+            self.log.error(
+                f'Improperly configured: "{absence_input}" is not a valid configuration! '
+                "Read the README for instructions.",
                 exc_info=True,
             )
             return False