fixes #16479

src/vs/workbench/parts/debug/common/debugModel.ts

@@ -72,7 +72,7 @@ export class OutputNameValueElement extends AbstractOutputElement implements deb
 	}
 
 	public get hasChildren(): boolean {
-		return Object.getOwnPropertyNames(this.valueObj).length > 0;
+		return isObject(this.valueObj) && Object.getOwnPropertyNames(this.valueObj).length > 0;
 	}
 
 	public getChildren(): TPromise<debug.IExpression[]> {

src/vs/workbench/parts/debug/electron-browser/replViewer.ts

@@ -40,7 +40,7 @@ export class ReplExpressionsDataSource implements IDataSource {
 	}
 
 	public hasChildren(tree: ITree, element: any): boolean {
-		return element instanceof Model || (<IExpressionContainer>element).hasChildren || element instanceof OutputNameValueElement;
+		return element instanceof Model || (<IExpressionContainer>element).hasChildren;
 	}
 
 	public getChildren(tree: ITree, element: any): TPromise<any> {