[model][variable] check for #21

pyheatpump/models/variable.py

@@ -81,6 +81,7 @@ class Variable(RowClass):
 
         return {
             row['address']: cast_fct(row['value'])
+
             for row in DB.sql(
             """SELECT var.address as address, val.value as value
             FROM variable var
@@ -94,6 +95,8 @@ class Variable(RowClass):
                 AND var.address <= :end_address
                 AND var.last_update > :since""",
             type.__dict__)
+
+            if row['address'] and row['value']
         }