Improve the function to find the next valid message after the delete
operation. This ensures that messages at the end or when marked in the
visual mode are properly dealt with.
Signed-off-by: Koni Marti <koni.marti@gmail.com>
Tested-by: Tim Culverhouse <tim@timculverhouse.com>
Acked-by: Robin Jarry <robin@jarry.cc>