The distinction between "warning" and "error" is highly arbitrary anyway. In C++, you also get a warning rather than an error if you, say, return a reference to a local, or read from an uninitialized local. You still get a binary, and it still runs. But these are 100% bugs, which is why most projects enable treat-warnings-as-errors for a lot of that stuff in C++. I'd imagine it's common with TypeScript, as well.