fix thermo None values

apps/nspanel-lovelace-ui/luibackend/helper.py

@@ -42,3 +42,7 @@ def rgb_dec565(rgb_color):
     # take in the red, green and blue values (0-255) as 8 bit values and then combine
     # and shift them to make them a 16 bit dec value in 565 format. 
     return ((int(red / 255 * 31) << 11) | (int(green / 255 * 63) << 5) | (int(blue / 255 * 31)))
+
+def get_attr_safe(entity, attr, default):
+    res = entity.attributes.get(attr, default) if not None else default
+    return res