From 0a614dfbc9a0b86570378151ca39584ce02e70a6 Mon Sep 17 00:00:00 2001
From: Durga <durga.sivakumar@shopify.com>
Date: Mon, 13 Apr 2026 12:52:12 -0400
Subject: [PATCH] Fix spread syntax runtime error on non-iterable values

Replace unsafe non-null assertions and truthy guards with Array.isArray
checks before spreading webhook subscription properties in
reduceWebhooks. Use flatMap with nullish coalescing in esbuild watcher
deleteContexts. Remove fragile Map.get()! in app-logs sources.

Add tests for reduceWebhooks property-branch merging, covering the case
where the existing subscription's property array is initially undefined.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
---
 .../transform/app_config_webhook.test.ts      | 30 +++++++++++++++++++
 .../transform/app_config_webhook.ts           | 10 +++----
 .../app/src/cli/services/app-logs/sources.ts  |  3 +-
 .../dev/app-events/app-watcher-esbuild.ts     |  2 +-
 4 files changed, 38 insertions(+), 7 deletions(-)

diff --git a/packages/app/src/cli/models/extensions/specifications/transform/app_config_webhook.test.ts b/packages/app/src/cli/models/extensions/specifications/transform/app_config_webhook.test.ts
index 93ef8ee8eba..660a65fdaa5 100644
--- a/packages/app/src/cli/models/extensions/specifications/transform/app_config_webhook.test.ts
+++ b/packages/app/src/cli/models/extensions/specifications/transform/app_config_webhook.test.ts
@@ -282,4 +282,34 @@ describe('reduceWebhooks', () => {
       },
     ])
   })
+
+  test('with property set, merges compliance_topics for subscriptions with the same uri', () => {
+    // Given
+    const subscriptions = [
+      {uri: 'https://example.com', compliance_topics: ['customers/redact']},
+      {uri: 'https://example.com', compliance_topics: ['customers/data_request']},
+    ]
+
+    // When
+    const result = reduceWebhooks(subscriptions, 'compliance_topics')
+
+    // Then
+    expect(result).toEqual([
+      {uri: 'https://example.com', compliance_topics: ['customers/redact', 'customers/data_request']},
+    ])
+  })
+
+  test('with property set, initializes the property array when existing subscription has none', () => {
+    // Given
+    const subscriptions = [
+      {uri: 'https://example.com'},
+      {uri: 'https://example.com', compliance_topics: ['customers/redact']},
+    ]
+
+    // When
+    const result = reduceWebhooks(subscriptions, 'compliance_topics')
+
+    // Then
+    expect(result).toEqual([{uri: 'https://example.com', compliance_topics: ['customers/redact']}])
+  })
 })
diff --git a/packages/app/src/cli/models/extensions/specifications/transform/app_config_webhook.ts b/packages/app/src/cli/models/extensions/specifications/transform/app_config_webhook.ts
index 45a4b6ba079..b34112362fa 100644
--- a/packages/app/src/cli/models/extensions/specifications/transform/app_config_webhook.ts
+++ b/packages/app/src/cli/models/extensions/specifications/transform/app_config_webhook.ts
@@ -80,15 +80,15 @@ export function reduceWebhooks(
   return subscriptions.reduce<WebhookSubscription[]>((accumulator, subscription) => {
     const existingSubscription = findSubscription(accumulator, subscription)
     if (existingSubscription) {
-      if (property && subscription?.[property]?.length) {
-        // eslint-disable-next-line @typescript-eslint/no-unnecessary-type-assertion
-        existingSubscription[property]?.push(...subscription[property]!)
+      if (property && Array.isArray(subscription?.[property]) && subscription[property].length) {
+        existingSubscription[property] ??= []
+        existingSubscription[property].push(...subscription[property])
       } else {
-        if (subscription.topics) {
+        if (Array.isArray(subscription.topics)) {
           existingSubscription.topics ??= []
           existingSubscription.topics.push(...subscription.topics)
         }
-        if (subscription.compliance_topics) {
+        if (Array.isArray(subscription.compliance_topics)) {
           existingSubscription.compliance_topics ??= []
           existingSubscription.compliance_topics.push(...subscription.compliance_topics)
         }
diff --git a/packages/app/src/cli/services/app-logs/sources.ts b/packages/app/src/cli/services/app-logs/sources.ts
index 7eb85f64540..3bf3c19ba34 100644
--- a/packages/app/src/cli/services/app-logs/sources.ts
+++ b/packages/app/src/cli/services/app-logs/sources.ts
@@ -15,7 +15,8 @@ export function sources(app: AppInterface) {
         sourcesByNamespace.set(sourceNamespace, [])
       }
 
-      sourcesByNamespace.set(sourceNamespace, [...sourcesByNamespace.get(sourceNamespace)!, source])
+      const existing = sourcesByNamespace.get(sourceNamespace) ?? []
+      sourcesByNamespace.set(sourceNamespace, [...existing, source])
     }
   })
 
diff --git a/packages/app/src/cli/services/dev/app-events/app-watcher-esbuild.ts b/packages/app/src/cli/services/dev/app-events/app-watcher-esbuild.ts
index edf39052082..afceb30f4c8 100644
--- a/packages/app/src/cli/services/dev/app-events/app-watcher-esbuild.ts
+++ b/packages/app/src/cli/services/dev/app-events/app-watcher-esbuild.ts
@@ -116,7 +116,7 @@ export class ESBuildContextManager {
   }
 
   async deleteContexts(extensions: ExtensionInstance[]) {
-    const promises = extensions.map((ext) => this.contexts[ext.uid]?.map((context) => context.dispose())).flat()
+    const promises = extensions.flatMap((ext) => this.contexts[ext.uid]?.map((context) => context.dispose()) ?? [])
     await Promise.all(promises)
     extensions.forEach((ext) => {
       const {[ext.uid]: _, ...rest} = this.contexts