Properly handle the case where `SpecializeType()` returns an error `Status`.

If the error case in `SpecializeType()` is reached, then we would get a crash when trying to access the value of an errorenous `StatusOr` object

PiperOrigin-RevId: 408380069
Change-Id: If3c3fc876dcf9384d5ec7a4985adc68c23ea7318