Type checking catches contradictions before execution, not every runtime failure

Type checkers compare operations against declared or inferred types without executing the program itself.

TypeScript defines this analysis as finding errors from the kinds of values being operated upon.

The strongest benefit is earlier feedback on incompatible assignments, arguments, returns, properties, and unreachable assumptions.

However, accepted code can still contain incorrect algorithms, stale requirements, race conditions, or environmental failures.

If Small unit tests give fast feedback checks behavior, CI gates every change early can enforce both tests and types.

These signals overlap occasionally, yet each one examines a substantially different model of correctness.

Treat type checking as a fast consistency proof, never as complete evidence that software behaves correctly.