1.3.0

Robustness, Safety, and Error Handling

🛡️ Major Robustness Improvements

This release makes SwiftMsgpack production-ready with comprehensive error handling and protection against malformed inputs.

🔒 Security & Safety

• Added max nesting depth guard (512 levels) to prevent stack overflow attacks from deeply nested payloads
• Added corrupt flag to MsgPackScanner for early detection of malformed inputs
• Bounds checking for all reads — no more out-of-bounds access on truncated data
• Integer overflow guards — values that don't fit the target type now throw instead of truncating
• UTF-8 validation — invalid UTF-8 strings now throw DecodingError instead of returning garbage

🐛 Critical Fixes

• Nil into non-optional — no longer crashes (now throws DecodingError)
• Empty data — now throws instead of crashing
• Data slices — now decode correctly without requiring a copy
• Truncated payloads — fixed-width, variable-length, and container headers all validate remaining bytes
• Huge claimed lengths (4GB+) — fail fast instead of exhausting memory
• Timestamp validation — negative nanoseconds and values ≥ 1e9 now throw

⚡ Performance

• Reserve capacity in encoder to reduce reallocations
• Container header size pre-calculation for more efficient writes
• loadUnaligned for safer and faster timestamp reading

🧪 Testing

Added comprehensive RobustnessTests suite covering:

• Truncated inputs
• Huge claimed lengths
• Deep nesting (200k levels)
• Nil into non-optional
• Invalid UTF-8
• Integer overflow
• Cross-format numeric interop
• Timestamp edge cases
• Data slice decoding

⚠️ Breaking Change

Decoding nil into non-optional types now throws DecodingError instead of returning nil. This aligns with Swift's standard JSONDecoder behavior and prevents silent data corruption.

// BEFORE: returned nil (crash on force unwrap)
let value = try decoder.decode(Int.self, from: Data([0xC0])) // 💥

// AFTER: throws DecodingError
let value = try decoder.decode(Int.self, from: Data([0xC0])) // ✅ throws