15b467f94e
Using exhaustive switch over type pairs ensures all combinations are handled. This is a follow-up to: https://dart-review.googlesource.com/c/sdk/+/379800 Change-Id: Ia6c4279a42590b439388d9fdd8ec5a8c36dbe23a Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/380560 Reviewed-by: Johnni Winther <johnniwinther@google.com> Commit-Queue: Chloe Stefantsova <cstefantsova@google.com>