improved code by mypy advice

governor.py

@@ -1,6 +1,6 @@
 from app_class import AppClass
 from config import Config
-from cpufreq import cpuFreq, cpufreq
+from cpufreq import cpuFreq, cpufreq  # type: ignore
 from functools import cached_property
 from mapping import governor_priority_mapping
 from exceptions import GovernorNotFound
@@ -46,6 +46,9 @@ class Governor(AppClass):
             self.log.warning("application is running in testmode, cpu governor not set")
             return None
         
+        if self._cpufreq is None:
+            return None
+        
         if governor_name not in self._cpufreq.available_governors:
             self.log.error("governor %s not supported by cpu", governor_name)
             return None