Addresses 14 of 21 remaining issues from third code review:
- Dead opcode stubs now error if reached; DynamicImport returns rejected Promise
- Missing exports throw at link time instead of silently returning undefined
- export * as ns from handled in resolve_reexports()
- Integration tests use execute_module() instead of execute_script()
- Parser rejects keyword imports without as, keyword exports without from
- Parser rejects duplicate default exports
- is_module propagated from Program AST to FunctionBlueprint
- Dead ScheduledScripts.module field and ModuleRecord.source removed
- Content-Type validation for module fetch (rejects HTML/image)
- execution_order_labels test helper uses deferred_order
- Interleaving test verifies actual array contents
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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