## Summary
You can now call `return_ty_result` to operate on a `Result` directly
thereby using your own diagnostics, as in:
```rust
return dunder_getitem_method
.call(self.db, &[slice_ty])
.return_ty_result(self.db, value.as_ref().into(), self)
.unwrap_or_else(|err| {
self.add_diagnostic(
(&**value).into(),
"call-non-callable",
format_args!(
"Method `__getitem__` is not callable on object of type '{}'.",
value_ty.display(self.db),
),
);
err.return_ty()
});
```