fixup! front: rework layer activation

Author: SarahBellaha

front/src/applications/editor/components/LayersModal.tsx

@@ -129,23 +129,20 @@ const LayersModal: FC<LayersModalProps> = ({
                   <SwitchSNCF
                     type="switch"
                     onChange={() => {
-                      const newSelectedLayersList = () => {
-                        const newSet = new Set(selectedLayers);
-                        layers.forEach((id) => {
-                          if (newSet.has(id)) newSet.delete(id);
-                          else newSet.add(id);
-                        });
-                        return newSet;
-                      };
-                      setSelectedLayers(newSelectedLayersList());
-                      dispatch(selectLayers(newSelectedLayersList()));
+                      const newSelectedLayersList = layers.reduce((result, layer) => {
+                        if (result.has(layer)) result.delete(layer);
+                        else result.add(layer);
+                        return result;
+                      }, new Set(selectedLayers));
+                      setSelectedLayers(newSelectedLayersList);
+                      dispatch(selectLayers(newSelectedLayersList));
                       dispatch(
                         updateLayersSettings({
                           ...layersSettings,
                           speedlimittag: speedLimitTag as string,
                         })
                       );
-                      onChange({ newLayers: newSelectedLayersList() });
+                      onChange({ newLayers: newSelectedLayersList });
                     }}
                     name={`editor-layer-${layerKey}`}
                     id={`editor-layer-${layerKey}`}