const state0 = {a: []};
const state1 = applyPatches(state0, [{op: "add", path: ["a","-"], value: 1}]);
const state2 = applyPatches(state1, [{op: "add", path: ["a","-"], value: 2}]);
const state3 = applyPatches(state2, [{op: "add", path: ["a","-"], value: 3}]);
console.log(state3);

per the JSON patch spec should produce state3 as:
{ a: [ 1, 2, 3 ] }

however, Immer produces state3 as:
{ a: [ 3, 2, 1 ] }

this is wrong. Immer is inserting at beginning instead of appending to the end