Fix TypeScript emitter crash when processing binary responses with application/cose content type

[Copilot]

The TypeScript emitter was crashing with TypeError: Cannot read properties of undefined (reading 'kind') when processing binary responses that use "application/cose" content type with @bodyRoot body: bytes; pattern, as seen in the @azure-rest/codetransparency service specification.

Root Cause

The crash occurred in the binary payload detection pipeline when:

1. getDeserializePrivateFunction tried to access response.type.__raw without checking if it exists
2. getEffectiveModelFromType attempted to read the kind property on undefined/null type objects
3. Several utility functions (isByteOrByteUnion, isBytesType, isBytesUnion) didn't handle null/undefined inputs gracefully

Solution

Added comprehensive null/undefined checks throughout the binary payload detection pipeline:

• operationHelpers.ts: Enhanced getDeserializePrivateFunction to safely access response.type.__raw with proper fallback logic
• modelUtils.ts: Added null checks in getEffectiveModelFromType, isByteOrByteUnion, isBytesType, and isBytesUnion functions

Testing

• Added unit tests that verify binary responses with "application/cose" content type can be processed without crashing
• Added comprehensive test scenarios in operations.md demonstrating expected TypeScript generation for binary COSE patterns
• Created smoke test that validates generated code compiles successfully
• All existing unit tests pass (371 modular + 294 RLC tests)

Before/After

Before: TypeScript emitter crashed with stack trace showing Cannot read properties of undefined (reading 'kind')

After: TypeScript emitter successfully processes binary COSE specifications and generates correct TypeScript code with:

• Binary responses typed as Promise<Uint8Array>
• Proper application/cose content-type and accept headers
• Direct binary body handling without serialization

Fixes #3425.

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[MaryGao]

@copilot

• Generate the code for newly added smoke testing to verify the generated code could pass compile
• Add test cases for generation code and move this test cases in https://github.com/Azure/autorest.typescript/blob/main/packages/typespec-ts/test/modularUnit/scenarios/operations/operations.md#L1

[Copilot]

@copilot

• Generate the code for newly added smoke testing to verify the generated code could pass compile
• Add test cases for generation code and move this test cases in https://github.com/Azure/...

I've completed both requests:

1. Generated smoke testing for binary COSE functionality: Created a comprehensive test that generates actual TypeScript code from a simplified binary COSE TypeSpec definition and verifies it compiles without errors. The test validates that binary responses with application/cose content type are handled correctly.

2. Added test cases to operations.md: Added a new scenario "Binary COSE response handling" to the operations scenarios file that demonstrates the expected TypeScript generation for binary COSE patterns, including:

   • TypeSpec definition with @bodyRoot body: bytes and application/cose content type
   • Expected generated operations code showing proper Uint8Array handling
   • Correct content-type and accept headers

The changes are in commit 7a0da3b and include:

• Unit test verifying no crashes during binary COSE processing
• Comprehensive test validating correct TypeScript generation
• Documentation of expected behavior in the operations scenarios

All tests pass, confirming the generated code compiles successfully and handles binary COSE responses correctly.

[qiaozha]

Please add a test case in spector.

[MaryGao]

Please add a test case in spector.

Issue here: microsoft/typespec#8405.