Can happen with TypeScript too. There is no runtime type checking so if you parsed a JSON object and cast some unknown property `const result = someRemoteObject

Can happen with TypeScript too. There is no runtime type checking so if you parsed a JSON object and cast some unknown property `const result = someRemoteObject.someUnknownPropertyWhichIsAString as number`, it doesn't guarantee that the result is actually a number. You still need to do actual schema validation just like with old school JavaScript.