[BUG] fastJsonPatch.compare with array generates wrong patches

[Jeremias Nater]

error scenario

The update on field "FirstName" is missing in this example:

const originalObject = JSON.parse(JSON.stringify(testObject));
testObject.array[1].firstName = 'NEW FIRSTNAME'; //changes second element
testObject.array.splice(0, 1); //removes first element
const patchesCompare = fastJsonPatch.compare(testObject, originalObject); // misses firstName Update value

Resulting Patches:

[
    {
        "op": "replace",
        "path": "/array/0/firstName",
        "value": "Peter"
    },
    {
        "op": "replace",
        "path": "/array/0/id",
        "value": "123zgasufczg2"
    },
    {
        "op": "add",
        "path": "/array/1",
        "value": {
            "id": "sad2241f12f12",
            "firstName": "Fritz"
        }
    }
]

issue demo on runkit

https://runkit.com/embed/rn5u4rs7ypup

var fastJsonPatch = require("fast-json-patch")

const testObject = {
    array: [
        {
            id: '123zgasufczg2',
            firstName: 'Peter'
        },
        {
            id: 'sad2241f12f12',
            firstName: 'Fritz'
        },
    ]
}

const originalObject = JSON.parse(JSON.stringify(testObject));

// observe
const patchObserver = fastJsonPatch.observe(testObject);

testObject.array[1].firstName = 'NEW FIRSTNAME'; //changes second element
testObject.array.splice(0, 1); //removes first element

// unobserve
const patchesObserve = fastJsonPatch.generate( patchObserver );
fastJsonPatch.unobserve( testObject, patchObserver );

// compare
const patchesCompare = fastJsonPatch.compare(testObject, originalObject);

// result, error
console.log("patches Observe:", patchesObserve);
console.log("patches Compare:", patchesCompare);
if (!patchesCompare.some(patch => patch.value == "NEW FIRSTNAME")) {
    console.log("this is the problem");
    throw new Error("COMPARE PATCH is missing change of 'NEW FIRSTNAME'")
}

[Tommy van der Vorst]

Could it be that the parameters to compare are in the wrong order? (i.e. compare(originalObject, testObject)?)