Forcing use of assign to modify context

[oriSomething]

Why doing that:

1. Makes library more opinionated about the way it should be used (currently it's only a suggestion)
2. Makes it easier to static analysis for linters, devtools and development version warnings
3. Makes flow more predictable (I'm not sure if I correct about this), as it might result differently if combing with manual context modifications (reference)
4. Allow us preventing mutation in places that shouldn't happen (For example: outside machine execution, or in some situations during invoke running)

Why not doing that:

1. It's a major breaking change as it might break some existing code bases (suggestions tends to be ignored)
2. Performance penalty (at least on development version)
3. There are some edge cases where someone need this loophole for performance reasons
4. It might won't play nicely with @xstate/immer

Consideration:

1. Should it be shallow or deep?
2. Proxy is probably the best way to implement it, but Proxy is still not fully supported on every engine, so there might be a good idea to allow to turn this validations off (It's possible to partly implement something such as this in ES5 compatible, but it's probably waste of time)
3. A way to bypass this protection (performance)?

References:

• twitter