In TypeScript 4.0, we allowed users to to annotate catch variables with : unknown; however, it'd be nice if we could have that be the default.

I could imagine a flag like --useUnknownInCatchVariables to switch the default type to be unknown.

// @useUnknownInCatchVariables: true

try {
  // ...
}
catch (e) {
  e.toUpperCase(); // error
}

Alternatively, I could also imagine a much broader flag that also types parameters as unknown as well.