diff --git a/src/vs/base/browser/ui/tree/dataTree.ts b/src/vs/base/browser/ui/tree/dataTree.ts
index e9e679a82356186032a5f0bfd90a0d37475eeef1..e112d9223cccf0446d798d6f60fa4045e3f192c3 100644
--- a/src/vs/base/browser/ui/tree/dataTree.ts
+++ b/src/vs/base/browser/ui/tree/dataTree.ts
@@ -207,7 +207,7 @@ export class DataTree<T extends NonNullable<any>, TFilterData = void> implements
 			slowTimeout.then(() => {
 				node.state = DataTreeNodeState.Slow;
 				this._onDidChangeNodeState.fire(node);
-			});
+			}, _ => null);
 
 			return this.dataSource.getChildren(node.element)
 				.then(children => {