stream: use an assertion for weird error cases
These two cases should only happen in case there's a bug in our implementation or the user manipulated things pretty bad. So instead of using our regular error system for these two cases, use a simple assertion.
I guess this should be semver-major even though it has always been just a sanity check (from the original implementation on).
@nodejs/streams PTAL
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