Remove key errors in _widget_destructors when finishing app

[LESSSE]

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• [ ] Title is descriptive/clear for inclusion in release notes.
• [ ] Applied a Component: xxx label.
• [ ] Applied the api-deprecation or api-break label.
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• [ ] Unittests are included in PR.
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[pythonic64]

Was this part of the code raising an error and if so do you have the code to reproduce that error? My concern is that we may hide the actual issue instead of fixing it.

[p0lygun]

@pythonic64 it is also happening in my project too, i'll try to make a minimal runnable

[LESSSE]

Error log sample:

Exception ignored in: functools.partial(<function _widget_destructor at 0x7ff2cf053a60>, 8952) Traceback (most recent call last): File "/home/lessse/Documents/facing/repos/deadpan_prototype/venv/lib/python3.8/site-packages/kivy/uix/widget.py", line 264, in _widget_destructor del _widget_destructors[uid] KeyError: 8952

This happens in a project using settings (SettingsWithSidebar). If during the app execution I open settings page, this error will spawn after closing the window. I suppose any small code using a settings page should show the error.

[p0lygun]

ooof forgot about this, I had a minimal runnable just forgot to update this issue Minimal runnable

import json
from kivy.app import App
from kivy.config import ConfigParser
from kivy.lang import Builder
from kivy.uix.settings import SettingsWithSidebar, Settings

settings_json = [
    {
        "type":"numeric",
        "title":"test",
        "key":"test",
        "section":"test"
    }
]

kv = """
Button:
    text:'Open settings'
    on_release:app.open_settings()
"""


class Test(App):
    def build(self):
        self.settings_cls = SettingsWithSidebar
        self.config.read('test.ini')
        self.config.write()
        return Builder.load_string(kv)

    def build_settings(self, settings: Settings):
        settings.add_json_panel(
            "App Settings",
            self.config,
            data=json.dumps(settings_json)
        )

    def build_config(self, config: ConfigParser):
        config.read('test.ini')
        config.adddefaultsection('test')
        config.setdefaults('test', {'test': 0})
        config.write()


if __name__ == '__main__':
    Test().run()

The error occurs the the app is closed
~~and that too only when a value id changed~~ No happens every time

[matham]

Ok, this is actually a bug in kivy, where we seemingly overwrite the widget uid in label = SettingSidebarLabel(text=name, uid=uid, menu=self) so we end up creating multiple widgets with the same uid. We need to fix the underlying issue.

[matham]

We may want to consider disabling setting the uid as a property, except with a specific method so it's not accidentally set. That would have prevented the issue as the current code would raise an exception rather than quietly accepting a custom uid.