read_mutation_from_flat_mutation_reader might throw
so we need to close the reader returned from
ms.make_fragment_v1_stream also on the error
path to avoid the internal error abort when the
reader is destroyed while opened.
Fixes#14098
Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
Closes#14099
bda3705974