fs: use `assert` in `fsCall` argument checking

In the user perspective, it's not an arguemnt type error. Replace it
with an `assert` expression.

PR-URL: https://github.com/nodejs/node/pull/38519
Refs: https://coverage.nodejs.org/coverage-68e6673224365120/lib/internal/fs/promises.js.html#L268


Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Darshan Sen <raisinten@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>