> A core type like the hash table should be high enough quality to avoid needing assertions bloating

Yes, and a core type implemented is also expected to be safe. If implemented unsafely, I expect assertions to come with it unless compiled with `--cfg ndebug`

> Furthermore, as a user of a hashtable, I don't expect it to bounds check

Yes, and as a user of a hashtable I expect it to be safe. These are just debug assertions, they should be compiled away with `--cfg ndebug`

> it's exceedingly likely that it be found during bootstrap/test

I disagree, bootstrapping is not equal to correct. It is *very* far from it.