fix issue with temp_fan that broke if show_power was True

ks_includes/screen_panel.py

@@ -179,7 +179,7 @@ class ScreenPanel:
             new_label_text += f"/{target:.0f}"
         if dev not in self.devices:
             new_label_text += "°"
-        if show_power:
+        if show_power and power:
             if lines == 2:
                 # The label should wrap, but it doesn't work
                 # this is a workaround