Previously, in order to assert that the promise was not resolved, an
error was thrown when the promise was resolved successfully. At the
same, `.catch()` was used to silence the (expected) promise rejection.
However, the chained `.catch()` handler would also catch (and swallow)
the error thrown on resolving the promise, making the test pass, even if
the promise was not rejected.
This commit fixes it by ensuring that the error thrown on resolving the
promise is not caught by the rejection handler.
PR Close#30515
848e53efd0