Record mutated variables / objects that might be mutated by a unknown loop or function call

[kaleidawave]

Given something like

function (cb: Function) {
    const obj = { a: 2 }
    cb(obj)
    console.log(obj.a)
}

This might fail if the function passed as cb deletes a from obj.

As there is no annotation syntax for marking a function as pure/without side effects (at the moment 👀) the safety isn't known inside the function.

This currently isn't caught in Ezno, so needs fixing.

Instead:

• Objects passed to functions (and some other items that might be mutated by calling a unknown function) must be marked as unstable or something
• Using this unstable poly types should require checking in apply_effect (as it evaluates side effects and is aware of what stage the function is at)

[kaleidawave]

#95 starts on this might need to identify the edge cases but the basic principal is there