From 960494436cf58b5c205a86aadb5bb813893ce93b Mon Sep 17 00:00:00 2001
From: Anton Kosyakov <anton.kosyakov@typefox.io>
Date: Mon, 22 Jul 2019 21:09:30 +0000
Subject: [PATCH] [plugin] restore previous tree view state before synching it

Signed-off-by: Anton Kosyakov <anton.kosyakov@typefox.io>
---
 packages/plugin-ext/src/main/browser/view/tree-views-main.ts | 2 ++
 packages/plugin-ext/src/plugin/tree/tree-views.ts            | 4 ++++
 2 files changed, 6 insertions(+)

diff --git a/packages/plugin-ext/src/main/browser/view/tree-views-main.ts b/packages/plugin-ext/src/main/browser/view/tree-views-main.ts
index 1ffe31eaf4b68..baf0b4db917f2 100644
--- a/packages/plugin-ext/src/main/browser/view/tree-views-main.ts
+++ b/packages/plugin-ext/src/main/browser/view/tree-views-main.ts
@@ -48,6 +48,8 @@ export class TreeViewsMainImpl implements TreeViewsMain {
             widget.model.viewInfo = viewInfo;
             if (state) {
                 widget.restoreState(state);
+                // ensure that state is completely restored
+                await widget.model.refresh();
             } else {
                 const root: CompositeTreeNode & ExpandableTreeNode = {
                     id: '',
diff --git a/packages/plugin-ext/src/plugin/tree/tree-views.ts b/packages/plugin-ext/src/plugin/tree/tree-views.ts
index b3dcecac272cb..85f69e1c0b3e1 100644
--- a/packages/plugin-ext/src/plugin/tree/tree-views.ts
+++ b/packages/plugin-ext/src/plugin/tree/tree-views.ts
@@ -164,6 +164,10 @@ class TreeViewExtImpl<T> extends Disposable {
     async getChildren(parentId: string): Promise<TreeViewItem[] | undefined> {
         // get element from a cache
         const parent = this.getTreeItem(parentId);
+        if (parentId && !parent) {
+            console.error(`No tree item with id '${parentId}' found.`);
+            return [];
+        }
 
         // ask data provider for children for cached element
         const result = await this.treeDataProvider.getChildren(parent);