Yes, that can happen. Just as a sound type system will also not prevent all possible bugs. So what? TypeScript's type system helps me to prevent many bugs by pe

Yes, that can happen. Just as a sound type system will also not prevent all possible bugs. So what? TypeScript's type system helps me to prevent many bugs by performing standard sanity checks, and is a very practical tool. Just rephrase your question as "How will a pervasive system of sanity checks help me prevent errors?", and I hope you agree that it kind of answers itself.