pn.Param: value doesn't have a value set #5751
Description
I'm on Panel 1.3.0 and Param 2.0 trying to refresh my understanding of the Location object https://panel.holoviz.org/how_to/state/url.html
When I try to create a small app from the example I get bokeh.core.property.descriptors.UnsetValueError: Slider(id='p1105', ...).value doesn't have a value set.
import param import panel as pn class QueryExample(param.Parameterized): integer = param.Integer(default=None, bounds=(0, 10)) string = param.String(default='A string') query_example = QueryExample() pn.state.location.sync(QueryExample(), {'integer': 'int', 'string': 'str'}) pn.Param(query_example).servable() File "/home/jovyan/repos/my-repo/.venv/lib/python3.10/site-packages/bokeh/core/has_props.py", line 599, in properties_with_values return self.query_properties_with_values(lambda prop: prop.serialized, File "/home/jovyan/repos/my-repo/.venv/lib/python3.10/site-packages/bokeh/core/has_props.py", line 656, in query_properties_with_values value = descriptor.get_value(self) File "/home/jovyan/repos/my-repo/.venv/lib/python3.10/site-packages/bokeh/core/property/descriptors.py", line 394, in get_value return self.__get__(obj, obj.__class__) File "/home/jovyan/repos/my-repo/.venv/lib/python3.10/site-packages/bokeh/core/property/descriptors.py", line 283, in __get__ raise UnsetValueError(f"{obj}.{self.name} doesn't have a value set") bokeh.core.property.descriptors.UnsetValueError: Slider(id='p1105', ...).value doesn't have a value setIf I change the integer value to 1 the example works.
I believe this is a bug and that pn.Param should pick another widget to support the None value.