Explorers raises error when data type changes

The sliders used for xlim/ylim are very sensitive to the initial data type .An example of this is if ylim sliders are calculated based on a number array, and then `y` is changed to a datetime array, it will raise an error.

https://user-images.githubusercontent.com/19758978/201969509-d8a33899-4468-490f-9686-10167ee65624.mp4

``` python
import numpy as np
import pandas as pd

data = dict(
x=np.arange(10),
y=np.arange(10) + 10,
t=pd.date_range("2020-01-01", freq="1d", periods=10),
)
df = pd.DataFrame(data)

hvplot.explorer(df)
```

``` python-traceback
Traceback (most recent call last):
File "/home/shh/miniconda3/envs/holoviz/lib/python3.10/site-packages/pyviz_comms/__init__.py", line 346, in _handle_msg
self._on_msg(msg)
File "/home/shh/Development/holoviz/repos/panel/panel/viewable.py", line 297, in _on_msg
doc.unhold()
File "/home/shh/miniconda3/envs/holoviz/lib/python3.10/site-packages/bokeh/document/document.py", line 799, in unhold
self.callbacks.unhold()
File "/home/shh/miniconda3/envs/holoviz/lib/python3.10/site-packages/bokeh/document/callbacks.py", line 396, in unhold
self.trigger_on_change(event)
File "/home/shh/miniconda3/envs/holoviz/lib/python3.10/site-packages/bokeh/document/callbacks.py", line 373, in trigger_on_change
invoke_with_curdoc(doc, event.callback_invoker)
File "/home/shh/miniconda3/envs/holoviz/lib/python3.10/site-packages/bokeh/document/callbacks.py", line 408, in invoke_with_curdoc
return f()
File "/home/shh/miniconda3/envs/holoviz/lib/python3.10/site-packages/bokeh/util/callback_manager.py", line 191, in invoke
callback(attr, old, new)
File "/home/shh/Development/holoviz/repos/panel/panel/reactive.py", line 403, in _comm_change
state._handle_exception(e)
File "/home/shh/Development/holoviz/repos/panel/panel/io/state.py", line 406, in _handle_exception
raise exception
File "/home/shh/Development/holoviz/repos/panel/panel/reactive.py", line 401, in _comm_change
self._schedule_change(doc, comm)
File "/home/shh/Development/holoviz/repos/panel/panel/reactive.py", line 383, in _schedule_change
self._change_event(doc)
File "/home/shh/Development/holoviz/repos/panel/panel/reactive.py", line 379, in _change_event
self._process_events(events)
File "/home/shh/Development/holoviz/repos/panel/panel/reactive.py", line 318, in _process_events
self.param.update(**self_events)
File "/home/shh/Development/holoviz/repos/param/param/parameterized.py", line 1898, in update
self_._batch_call_watchers()
File "/home/shh/Development/holoviz/repos/param/param/parameterized.py", line 2059, in _batch_call_watchers
self_._execute_watcher(watcher, events)
File "/home/shh/Development/holoviz/repos/param/param/parameterized.py", line 2021, in _execute_watcher
watcher.fn(*args, **kwargs)
File "/home/shh/Development/holoviz/repos/panel/panel/param.py", line 496, in link_widget
self.object.param.update(**{p_name: change.new})
File "/home/shh/Development/holoviz/repos/param/param/parameterized.py", line 1898, in update
self_._batch_call_watchers()
File "/home/shh/Development/holoviz/repos/param/param/parameterized.py", line 2059, in _batch_call_watchers
self_._execute_watcher(watcher, events)
File "/home/shh/Development/holoviz/repos/param/param/parameterized.py", line 2021, in _execute_watcher
watcher.fn(*args, **kwargs)
File "/home/shh/Development/holoviz/repos/param/param/parameterized.py", line 669, in caller
return function()
File "/home/shh/Development/holoviz/repos/param/param/parameterized.py", line 407, in _depends
return func(*args, **kw)
File "/home/shh/Development/holoviz/repos/hvplot/hvplot/ui.py", line 189, in _update_ranges
self.param.ylim.bounds = ylim
File "/home/shh/Development/holoviz/repos/param/param/parameterized.py", line 1137, in __setattr__
self.owner.param._call_watcher(watcher, event)
File "/home/shh/Development/holoviz/repos/param/param/parameterized.py", line 2039, in _call_watcher
self_._execute_watcher(watcher, (event,))
File "/home/shh/Development/holoviz/repos/param/param/parameterized.py", line 2021, in _execute_watcher
watcher.fn(*args, **kwargs)
File "/home/shh/Development/holoviz/repos/panel/panel/param.py", line 588, in link
widget.param.update(**updates)
File "/home/shh/Development/holoviz/repos/param/param/parameterized.py", line 1898, in update
self_._batch_call_watchers()
File "/home/shh/Development/holoviz/repos/param/param/parameterized.py", line 2059, in _batch_call_watchers
self_._execute_watcher(watcher, events)
File "/home/shh/Development/holoviz/repos/param/param/parameterized.py", line 2021, in _execute_watcher
watcher.fn(*args, **kwargs)
File "/home/shh/Development/holoviz/repos/panel/panel/reactive.py", line 308, in _param_change
self._apply_update(named_events, msg, model, ref)
File "/home/shh/Development/holoviz/repos/panel/panel/reactive.py", line 240, in _apply_update
self._update_model(events, msg, root, model, doc, comm)
File "/home/shh/Development/holoviz/repos/panel/panel/widgets/slider.py", line 95, in _update_model
return super()._update_model(events, msg, root, model, doc, comm)
File "/home/shh/Development/holoviz/repos/panel/panel/reactive.py", line 263, in _update_model
model.update(**msg)
File "/home/shh/miniconda3/envs/holoviz/lib/python3.10/site-packages/bokeh/core/has_props.py", line 413, in update
setattr(self, k, v)
File "/home/shh/miniconda3/envs/holoviz/lib/python3.10/site-packages/bokeh/core/has_props.py", line 230, in __setattr__
return super().__setattr__(name, value)
File "/home/shh/miniconda3/envs/holoviz/lib/python3.10/site-packages/bokeh/core/property/descriptors.py", line 283, in __set__
value = self.property.prepare_value(obj, self.name, value)
File "/home/shh/miniconda3/envs/holoviz/lib/python3.10/site-packages/bokeh/core/property/bases.py", line 365, in prepare_value
raise ValueError(f"failed to validate {obj_repr}.{name}: {error}")
ValueError: failed to validate RangeSlider(id='13053', ...).start: expected a value of type Real, got 2020-01-01T00:00:00.000000000 of type datetime64
```