stream: remove TODO and add a description instead
After looking into this it turned out that these two errors are
sanity checks that should not be reached. It is unfortunate that
we assigned error codes for these but changing it into an assertion
seems to be a hassle for readable-streams
.
Checklist
-
make -j4 test
(UNIX), orvcbuild test
(Windows) passes -
tests and/or benchmarks are included -
documentation is changed or added -
commit message follows commit guidelines