Layer.remove() should properly remove from parent LayerGroup

[quarl]

Checklist

• I've looked at the documentation to make sure the behavior isn't documented and expected.
• I'm sure this is an issue with Leaflet, not with my app or other dependencies (Angular, Cordova, React, etc.).
• I've searched through the current issues to make sure this hasn't been reported yet.
• I agree to follow the Code of Conduct that this project adheres to.

Steps to reproduce

Code:

1. Create a LayerGroup and add to the map.
2. Create some layer, e.g. a Marker, and add to the LayerGroup.
3. Call layer.remove()
4. Remove the LayerGroup.
5. Add the LayerGroup back.

const map = L.map('map', {
	layers: [L.tileLayer('https://tile.openstreetmap.org/{z}/{x}/{y}.png')],
	center: [51, 0.02], zoom: 14
});

const layerGroup = L.layerGroup().addTo(map);
L.control.layers(null, { 'Notice that clicking off and on introduces a middle marker': layerGroup }, {collapsed: false}).addTo(map);
const marker1 = L.circleMarker([51, 0.01]).addTo(layerGroup);
const marker2 = L.circleMarker([51, 0.02]).addTo(layerGroup);
const marker3 = L.circleMarker([51, 0.03]).addTo(layerGroup);
// Layer.remove() is buggy.  It removes from the Map but not the
// LayerGroup that it's in.  If we remove the LayerGroup and add the
// LayerGroup back (for example using L.Control.Layers), then the marker 
// reappears; whereas layerGroup.removeLayer() correctly removes from
// both LayerGroup and Map.
marker2.remove();

Expected behavior

I expected that layer.remove() removes from the map AND from the layerGroup that it's in, such that it remains removed if the layerGroup is removed and re-added.

Current behavior

As of Leaflet 1.9.4, Layer.remove() removes the layer from layer._map._layers, but does not remove from layerGroup._layers, for the layerGroup that it's in.
The layer gets removed from DOM and visually disappears.
However, if you remove the LayerGroup and add it back (for example via Layers Control), then the supposedly removed layer reappears (because it was never removed from layerGroup._layers).

Minimal example reproducing the issue

https://plnkr.co/edit/iYrvKIpBwRsUtYd2?preview

Environment

• Leaflet version: 1.9.4
• Browser (with version): Chrome 120.0.6099.129 , Firefox 121.0
• OS/Platform (with version): Mac

[bre01]

According to the docs, layer only removed from map but kept in group is expected behavior.
https://leafletjs.com/reference.html#circlemarker-remove.
You can instead use removeFrom method to remove the layer from group.
https://leafletjs.com/reference.html#circlemarker-removefrom

[quarl]

Regardless of whether it's what's currently documented, it seems like unintuitive behavior to me. It puts the objects into an inconsistent state.

[IvanSanchez]

You gotta realize that a L.Layer can belong to several L.LayerGroups at once, and that there can be nested L.LayerGroups.

The logic could be different, but there's no one-size-fits-all solution that will make everybody happy.