fix: lazy format values that evalute to bool-False are not rendered (…

…mainly an issue with 0)

htmlgenerator/base.py

@@ -353,7 +353,8 @@ def get_value(self, key, args, kwds):
         def extract(value):
             if isinstance(value, BaseElement):
                 return render(value, self.context)
-            return resolve_lazy(value, self.context) or ""
+            v = resolve_lazy(value, self.context)
+            return "" if v is None else v
 
         ret = super().get_value(
             key,