handled None return for temp

pyfan.py

@@ -35,6 +35,7 @@ class ThermalZone:
                                                                                         self.pid.Kd)))
 
     def eval(self):
+        if self.get_temp():
             diff = self.target - self.get_temp()
             val = self.pid(diff)
 
@@ -58,7 +59,10 @@ class ThermalZone:
                                                                          d=int(d)))
 
     def get_temp(self):
+        if self.read_sysfs(self.temp_source):
             return float(self.read_sysfs(self.temp_source)) * self.factor
+        else:
+            return None
 
     def restore(self):
         self.setup_pwm(2)
@@ -94,6 +98,7 @@ class ThermalZone:
             logging.getLogger("pyfan").warning(
                 "[%s] temp source not found. Not ready yet or wrong path? (%s)" % (self.name,
                                                                                    err.strerror))
+            return None
 
     def set_pwm_mode(self, path, value=1):
         self.write_sysfs(path + "_enable", value)