TypeScript strict mode is off — whole classes of bugs go undetected

What it is

TypeScript is configured with strict off, or with individual strict flags such as strictNullChecks disabled.

Why it matters

Without strictNullChecks the compiler treats every value as present, so the undefined that arrives at runtime was never going to be caught. The types read as if they are checked while checking very little.

How to fix it

Turn strict on and work through the errors — most are genuine missing null handling. On a large codebase, enable it for new files first via an override, then migrate directories one at a time.