TypeScript strict mode or equivalent linting is enabled

TypeScript without strict: true is a false sense of safety. With strictNullChecks disabled, the compiler allows null and undefined to be passed anywhere — silently — meaning null pointer exceptions lurk undetected until runtime. With noImplicitAny disabled, entire code paths go untyped. CWE-704 (Incorrect Type Conversion or Cast) applies: the type system fails to catch conversions that will break at runtime. ISO 25010 maintainability.analysability and modifiability both degrade when developers cannot trust the type system to catch refactoring errors.

Enable strict mode in tsconfig.json:

{
  "compilerOptions": {
    "strict": true
  }
}

If enabling strict mode surfaces many errors in an existing codebase, add flags incrementally: "noImplicitAny": true first, fix those errors, then "strictNullChecks": true. Each flag catches a distinct class of real bugs — budget time to address them, because they were already there.