Doc Tooltip disappears on invalid input

[ahuang11]

import param
import panel as pn
pn.extension()

class Test(param.Parameterized):

    d = param.Dict(doc="This should not disappear")

pn.Param(Test)

Before

After invalid input

I think it's on LiteralInput:

    def _process_property_change(self, msg):
        msg = super()._process_property_change(msg)
        new_state = ''
        if 'value' in msg:
            value = msg.pop('value')
            try:
                if value == '':
                    value = ''
                elif self.serializer == 'json':
                    value = json.loads(value)
                else:
                    value = ast.literal_eval(value)
            except Exception:
                new_state = ' (invalid)'
                value = self.value