Fix spread syntax runtime error on non-iterable values

[durga256]

Summary

• Guard array spread sites that could receive non-iterable values at runtime, fixing "Spread syntax requires ...iterable[Symbol.iterator] to be a function" errors reported by Observe (7 events, 2 users over 7 days)
• Replace ! non-null assertions and truthy checks with Array.isArray guards in reduceWebhooks webhook config transform — also fixes a silent data-loss bug where topics were dropped when existingSubscription[property] was undefined (the old ?.push would silently no-op)
• Replace .map().flat() with .flatMap(... ?? []) in esbuild watcher deleteContexts to handle missing context entries
• Remove fragile Map.get()! pattern in app-logs sources by using ?? [] fallback
• Add tests for reduceWebhooks property-branch merging, covering the ??= [] initialization case

Why

Observe reports a "Spread syntax requires ...iterable[Symbol.iterator] to be a function" runtime error in the app slice. The strongest candidate is reduceWebhooks in the webhook config transform, where subscription data is spread using ! non-null assertions — if the data has unexpected shape, the spread throws. The Map.get()! in sources.ts is the only such pattern in the codebase and is fragile if the has() guard above is ever refactored away. The esbuild watcher uses flatMap as the idiomatic replacement for optional-chaining inside .map().flat().

Test plan

• pnpm vitest run packages/app/src/cli/models/extensions/specifications/transform/app_config_webhook.test.ts — 9 tests pass (7 existing + 2 new)
• pnpm vitest run packages/app/src/cli/services/dev/app-events/app-watcher-esbuild.test.ts — 8 tests pass
• pnpm vitest run packages/app/src/cli/services/app-logs/sources.test.ts — 1 test passes
• TypeScript compilation — no new errors in changed files

[durga256]

• Fix spread syntax runtime error on non-iterable values #7271 👈 (View in Graphite)
• main

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[Copilot]

Pull request overview

Fixes a reported runtime error caused by spreading non-iterable values by adding safer array guards in webhook config transforms, and applies similar defensive patterns in a couple of other collection/iteration sites in the CLI.

Changes:

• Harden reduceWebhooks merging logic using Array.isArray + ??= [] initialization to avoid spread/runtime errors and prevent silent no-op merges.
• Simplify esbuild watcher cleanup by switching from .map().flat() to .flatMap(... ?? []) when contexts may be missing.
• Remove a fragile non-null assertion in log source grouping by using a ?? [] fallback, and add tests for the webhook reducer behavior.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
packages/app/src/cli/services/dev/app-events/app-watcher-esbuild.ts	Makes deleteContexts robust when an extension has no contexts entry by using flatMap with a safe fallback.
packages/app/src/cli/services/app-logs/sources.ts	Replaces Map.get()! with ?? [] to avoid potential runtime exceptions if the has()/set() logic changes.
packages/app/src/cli/models/extensions/specifications/transform/app_config_webhook.ts	Adds Array.isArray guards and initializes missing arrays before pushing to avoid spread-related runtime errors and data loss.
packages/app/src/cli/models/extensions/specifications/transform/app_config_webhook.test.ts	Adds tests covering property-based merging and initialization behavior in reduceWebhooks.

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