What is sound null safety in Dart?

Summary

Types are non-nullable by default; T? allows null. The compiler forces null checks before using nullable values and guarantees non-nullable variables never hold null at runtime.

Longer Answer

Use ?., ?? and ??=, rely on type promotion after checks, and keep the ! operator and late for rare cases.

Key Points

• Non-nullable by default.
• Flow analysis promotes after checks.
• ! and late can still fail at runtime.

Deep dive: Dart Fundamentals: Null Safety