fix: handle undefined functionTypeMapping in all protocol generators

[jonaslagoni]

Summary

Fix a crash bug where all protocol generators (NATS, Kafka, MQTT, AMQP, WebSocket, EventSource, HTTP) throw Cannot read properties of undefined (reading 'channel_id') when generator.functionTypeMapping is undefined instead of the expected empty object {}.

Type of Change

• New feature (adds functionality)
• Bug fix (fixes an issue)
• Breaking change (changes existing functionality)
• Documentation update
• Performance improvement
• Refactoring (no functional changes)
• Test improvements

Changes Made

New Files

• test/codegen/generators/typescript/channels/protocols/functionTypeMapping.spec.ts - Unit tests verifying all 7 protocol generators handle undefined functionTypeMapping gracefully

Modified Files

• src/codegen/generators/typescript/channels/protocols/nats/index.ts - Added optional chaining at lines 115, 328
• src/codegen/generators/typescript/channels/protocols/kafka/index.ts - Added optional chaining at lines 100, 185
• src/codegen/generators/typescript/channels/protocols/mqtt/index.ts - Added optional chaining at lines 98, 160
• src/codegen/generators/typescript/channels/protocols/amqp/index.ts - Added optional chaining at lines 99, 195
• src/codegen/generators/typescript/channels/protocols/websocket/index.ts - Added optional chaining at lines 109, 211
• src/codegen/generators/typescript/channels/protocols/eventsource/index.ts - Added optional chaining at lines 100, 191
• src/codegen/generators/typescript/channels/protocols/http/index.ts - Added optional chaining at line 113

Key Implementation Details

Root Cause

The bug occurs because:

1. The Zod schema defines functionTypeMapping with .optional().default({})
2. This default is applied during Zod parsing
3. However, when functionTypeMapping: undefined is explicitly set (not missing), spread operators preserve undefined
4. All protocol generators access generator.functionTypeMapping[channel.id()] without checking if functionTypeMapping exists

Fix

Added optional chaining (?.) at all 13 access points across 7 protocol generators:

// Before (crashes)
const functionTypeMapping = generator.functionTypeMapping[channel.id()];

// After (safe)
const functionTypeMapping = generator.functionTypeMapping?.[channel.id()];

Testing

Unit Tests (TDD)

✅ Tests written BEFORE implementation and verified to FAIL:

TypeError: Cannot read properties of undefined (reading 'user/signedup')

✅ Tests PASS after implementation:

PASS test/codegen/generators/typescript/channels/protocols/functionTypeMapping.spec.ts
  functionTypeMapping undefined bug
    should handle undefined functionTypeMapping without crashing
      ✓ NATS generator (6 ms)
      ✓ Kafka generator (1 ms)
      ✓ MQTT generator (1 ms)
      ✓ AMQP generator
      ✓ WebSocket generator
      ✓ EventSource generator
      ✓ HTTP client generator (7 ms)
      ✓ all protocols together (1 ms)

Test Suites: 1 passed, 1 total
Tests:       8 passed, 8 total

Full Test Suite

✅ All unit tests pass: npm run test

Build

✅ Build succeeds: npm run build

Lint

✅ Lint passes: npm run lint

Runtime Generate

✅ Runtime code generates successfully: npm run runtime:typescript:generate

Breaking Changes

None - This is a purely additive defensive fix using optional chaining. Existing behavior is unchanged for valid configurations.

Checklist

• Code follows project conventions
• All tests pass (unit, blackbox, runtime)
• No TypeScript errors
• Lint passes
• Build succeeds
• Follows existing patterns
• Tests verify the bug existed and is now fixed (TDD)

Verification

After implementation, verified no unguarded access remains:

# Should return 0 results (no unguarded access)
rg "generator\.functionTypeMapping\[" src/codegen/generators/typescript/channels/protocols/
# Result: No matches found ✓

# Should show 13 guarded accesses
rg "generator\.functionTypeMapping\?\.\[" src/codegen/generators/typescript/channels/protocols/
# Result: 13 matches ✓

🤖 Generated with Claude Code

---

Note

Low Risk
Low risk: small defensive change (optional chaining) in TypeScript channel codegen; main risk is minor behavior change in how default function-type filtering is applied when the mapping is missing/undefined.

Overview
Prevents crashes in the TypeScript channels codegen when generator.functionTypeMapping is explicitly undefined by switching all protocol generators (AMQP, EventSource, HTTP client, Kafka, MQTT, NATS, WebSocket) to use optional-chained lookups (generator.functionTypeMapping?.[channel.id()]).

Adds a Jest regression test that runs generateTypeScriptChannels across each protocol (and a combined run) with functionTypeMapping forced to undefined, asserting generation completes without throwing.

^{Reviewed by Cursor Bugbot for commit 7984353. Bugbot is set up for automated code reviews on this repo. Configure here.}

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[jonaslagoni]

🎉 This PR is included in version 0.70.1 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

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