This is wrong. WebAssembly doesn't care where you write inside the arena.
See: https://gist.github.com/fwsGonzo/8d8d0d27847c2d5804bc2d8af2b...
.. but it is safe to write anywhere in the arena!
See: https://gist.github.com/fwsGonzo/8d8d0d27847c2d5804bc2d8af2b...
.. but it is safe to write anywhere in the arena!