But then the problem is on "how to not lose your code", not in FFI...��

Restarting image is a problem. For any other "smalltalk" problems we got suitable debugger but not in that case.

Also when image crashed we need to recover all objects state for the script which produce crash

FFI is a border.

Once you start working with it, you are in C world.��

And C world is nasty, hard and cumbersome.