src: turn buffer type-CHECK into exception

Turn a `CHECK()` that could be brought to fail using public APIs
into throwing an error.

Fixes: https://github.com/nodejs/node/issues/12152
PR-URL: https://github.com/nodejs/node/pull/12753


Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Timothy Gu <timothygu99@gmail.com>
Reviewed-By: Refael Ackermann <refack@gmail.com>