Fix layer removal bug (geojupyter#101)

Author: gjmooney

packages/base/src/commands.ts

@@ -529,7 +529,7 @@ export function addCommands(
     execute: () => {
       const model = tracker.currentWidget?.context.model;
       Private.removeSelectedItems(model, 'layer', selection => {
-        model?.sharedModel.removeLayer(selection);
+        model?.removeLayer(selection);
       });
     }
   });

packages/schema/src/interfaces.ts

@@ -162,6 +162,7 @@ export interface IJupyterGISModel extends DocumentRegistry.IModel {
     groupName?: string,
     position?: number
   ): void;
+  removeLayer(id: string): void;
   getOptions(): IJGISOptions;
   setOptions(value: IJGISOptions): void;
 

packages/schema/src/model.ts

@@ -343,6 +343,11 @@ export class JupyterGISModel implements IJupyterGISModel {
     this._addLayerTreeItem(id, groupName, position);
   }
 
+  removeLayer(layer_id: string) {
+    this._removeLayerTreeLayer(this.getLayerTree(), layer_id);
+    this.sharedModel.removeLayer(layer_id);
+  }
+
   setTerrain(terrain: IJGISTerrain) {
     this._sharedModel.terrain = terrain;
   }