Fix #43466

src/vs/workbench/api/node/extHostTreeViews.ts

@@ -197,7 +197,7 @@ class ExtHostTreeView<T> extends Disposable {
 		}
 
 		const prefix = parentHandle ? parentHandle : ExtHostTreeView.LABEL_HANDLE_PREFIX;
-		let elementId = label ? label : basename(resourceUri.path);
+		let elementId = label ? label : resourceUri ? basename(resourceUri.path) : '';
 		elementId = elementId.indexOf('/') !== -1 ? elementId.replace('/', '//') : elementId;
 		const existingHandle = this.nodes.has(element) ? this.nodes.get(element).handle : void 0;
 

src/vs/workbench/browser/parts/views/customView.ts

@@ -404,7 +404,7 @@ class TreeRenderer implements IRenderer {
 
 	public renderElement(tree: ITree, node: ITreeItem, templateId: string, templateData: ITreeExplorerTemplateData): void {
 		const resource = node.resourceUri ? URI.revive(node.resourceUri) : null;
-		const name = node.label || basename(resource.path);
+		const name = node.label ? node.label : resource ? basename(resource.path) : '';
 		const icon = this.themeService.getTheme().type === LIGHT ? node.icon : node.iconDark;
 
 		// reset