Fix fetch client to intercept AbortError and other fetch exceptions

Summary

Fixed an issue where the fetch client was not intercepting exceptions thrown by the fetch call, such as AbortError (when a request is aborted) and network errors. These exceptions were propagating directly to the caller without going through error interceptors, unlike HTTP errors which were properly handled.

Changes

Main Fix (client.ts)

• Wrapped the await _fetch(request) call in a try-catch block
• When fetch throws an exception:
  • The error is passed through all registered error interceptors
  • If throwOnError is true, the transformed error is re-thrown
  • Otherwise, returns an error response object consistent with HTTP error handling

Tests (client.test.ts)

Added 4 comprehensive tests for exception handling:

• Test that AbortError is intercepted and passed through error interceptors
• Test that network errors are intercepted and passed through error interceptors
• Test that with throwOnError: true, the transformed error is thrown
• Test that without error interceptors, the original error is returned

Updates

• Built packages
• Updated 143 snapshot files with the new client code
• Regenerated all 14 examples with updated client code
• All tests passing (610 tests)

Verification Results

• All 27 tests in client.test.ts pass ✅
• All 610 tests in openapi-ts-tests pass ✅
• All 14 examples regenerated ✅
• TypeScript compilation succeeds ✅
• Linting passes ✅
• Build succeeds ✅

Behavior

Before: AbortError and network errors would throw directly, bypassing error interceptors
After: All fetch exceptions are caught, passed through error interceptors, and handled consistently

• Fixes fetch client doesn't intercept AbortError #2969

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