Invariant: cannot mutate a havoced object

[gaearon]

Test:

(function() {
  var someAbstract = global.__abstract ? __abstract("function", '(function() {})') : () => {};
  var evaluatePureFunction = global.__evaluatePureFunction || (f => f());
  
  var result;
  evaluatePureFunction(() => {
    function calculate(y) {
      var z = {c: 3, e: 1};
      if (global.__makePartial) __makePartial(z);
      if (global.__makeSimple) __makeSimple(z);  
      someAbstract(z);

      var x = {a: 1, b: 1, c: 1};
      return Object.assign(x, y, z);
    }
    result = calculate({b: 2, d: 1});
  });
  
  global.inspect = function() {
    return JSON.stringify(result);
  };
})();

Invariant:

cannot mutate a havoced object

This is likely a bug in Prepack, not your code. Feel free to open an issue on GitHub.
    at invariant (/Users/gaearon/p/prepack/src/invariant.js:16:15)
    at ObjectValue.set (/Users/gaearon/p/prepack/src/values/ObjectValue.js:153:21)
    at ObjectValue.makeNotPartial (/Users/gaearon/p/prepack/src/values/ObjectValue.js:357:5)
    at NativeFunctionValue.func.defineNativeMethod [as callback] (/Users/gaearon/p/prepack/src/intrinsics/ecma262/Object.js:100:15)
    at NativeFunctionValue.callCallback (/Users/gaearon/p/prepack/src/values/NativeFunctionValue.js:120:12)
    at OrdinaryCallEvaluateBody (/Users/gaearon/p/prepack/src/methods/call.js:299:16)
    at InternalCall (/Users/gaearon/p/prepack/src/methods/function.js:115:39)
    at FunctionImplementation.$Call (/Users/gaearon/p/prepack/src/methods/function.js:857:12)
    at NativeFunctionValue.$Call (/Users/gaearon/p/prepack/src/values/NativeFunctionValue.js:52:24)
    at Call (/Users/gaearon/p/prepack/src/methods/call.js:572:12)

It fails because of this trick which won't work if the object is havoced. But it seems like this is weird code regardless. If $OwnPropertyKeys needs to work on a partial in this case, it would make more sense to me if we disabled this contextually in $OwnPropertyKeys itself instead of temporarily changing the object's status.