From 9dffdd744dea0ee4942029bad2c62943710153d2 Mon Sep 17 00:00:00 2001
From: Doug Parker <dgp1130@users.noreply.github.com>
Date: Fri, 14 Mar 2025 15:46:17 -0700
Subject: [PATCH] refactor(devtools): fix reading `resolutionPath` (#60403)

Sometimes `forest` can be empty if the provided roots are empty, and was leading to a "Cannot read `resolutionPath` of `undefined`" error. Now we check the forest has a tree in it before looking up `resolutionPath`.

There might be a separate issue with the fact that the backend script likely shouldn't be emitting an empty forest in the first place. However we already check that a resolution path exists at all, so I think it's fair to also check that a tree was provided. We can separately look into making sure the backend is emitting valid data.

PR Close #60403
---
 .../src/lib/client-event-subscribers.ts            | 14 ++++++++------
 .../injector-tree/injector-tree.component.ts       | 12 +++++++-----
 2 files changed, 15 insertions(+), 11 deletions(-)

diff --git a/devtools/projects/ng-devtools-backend/src/lib/client-event-subscribers.ts b/devtools/projects/ng-devtools-backend/src/lib/client-event-subscribers.ts
index 3f0049c37d2..9c81935b24c 100644
--- a/devtools/projects/ng-devtools-backend/src/lib/client-event-subscribers.ts
+++ b/devtools/projects/ng-devtools-backend/src/lib/client-event-subscribers.ts
@@ -222,13 +222,15 @@ const getRoutes = (messageBus: MessageBus<Events>) => {
     initializeOrGetDirectiveForestHooks().getIndexedDirectiveForest(),
     ngDebugDependencyInjectionApiIsSupported(),
   );
+  if (forest.length === 0) return;
+
   const rootInjector = (forest[0].resolutionPath ?? []).find((i) => i.name === 'Root');
-  if (rootInjector) {
-    const route = getRouterConfigFromRoot(rootInjector);
-    if (route) {
-      messageBus.emit('updateRouterTree', [[route]]);
-    }
-  }
+  if (!rootInjector) return;
+
+  const route = getRouterConfigFromRoot(rootInjector);
+  if (!route) return;
+
+  messageBus.emit('updateRouterTree', [[route]]);
 };
 
 const getSerializedProviderRecords = (injector: SerializedInjector) => {
diff --git a/devtools/projects/ng-devtools/src/lib/devtools-tabs/injector-tree/injector-tree.component.ts b/devtools/projects/ng-devtools/src/lib/devtools-tabs/injector-tree/injector-tree.component.ts
index 3c838c666ad..22faaad7373 100644
--- a/devtools/projects/ng-devtools/src/lib/devtools-tabs/injector-tree/injector-tree.component.ts
+++ b/devtools/projects/ng-devtools/src/lib/devtools-tabs/injector-tree/injector-tree.component.ts
@@ -91,11 +91,13 @@ export class InjectorTreeComponent {
 
   private init() {
     this._messageBus.on('latestComponentExplorerView', (view: ComponentExplorerView) => {
-      if (view.forest[0].resolutionPath !== undefined) {
-        this.diDebugAPIsAvailable.set(true);
-        this.rawDirectiveForest = view.forest;
-        this.updateInjectorTreeVisualization(view.forest);
-      }
+      if (view.forest.length === 0) return;
+
+      if (!view.forest[0].resolutionPath) return;
+
+      this.diDebugAPIsAvailable.set(true);
+      this.rawDirectiveForest = view.forest;
+      this.updateInjectorTreeVisualization(view.forest);
     });
 
     this._messageBus.on(