Replace op with value of empty object results in circular reference

[blairlunceford]

Describe the bug
We've seen Azure AD SCIM send replace operations with an empty object in the value field:

{
  op: 'replace',
  path: 'phoneNumbers[type eq "work"].value',
  value: {},
}

They sometimes send this operation when there isn't a multi-valued attribute of that type. When this happens, the scim-patch library applies the update in a way that introduces a circular reference to the resource object. This causes errors when we call JSON.stringify on the resource object.

To Reproduce

const scimPatch = require("scim-patch")
const assert = require("assert")

const resource = {
   phoneNumbers: [
    {
      type: 'mobile',
      value: '7865439908',
    },
  ],
}

const operation = {
  op: 'replace',
  path: 'phoneNumbers[type eq "work"].value',
  value: {},
}

const expected = {
  phoneNumbers: [
    {
      type: 'mobile',
      value: '7865439908',
    },
    {
      type: 'work',
      value: {},
    },
  ],
}

const patchedResource = scimPatch.scimPatch(resource, [operation], { mutateDocument: false, treatMissingAsAdd: true },)

assert.deepStrictEqual(patchedResource, expected)

console.log(patchedResource);
=> {
      phoneNumbers: [
        { type: 'mobile', value: '7865439908' },
        { type: 'work', value: [Circular *1] }
      ]
    }

Expected behavior
We would expect operations to be applied to resources in a way that doesn't introduce a circular reference in the object. Though, admittedly, this update is a bit strange from Azure AD SCIM (the value should be a string here I believe, and this only seems to happen with an empty object).

Additional context
We wanted to flag this in the upstream library. We're currently looking at workarounds on our end to either edit the resource before sending it to the library, or checking for circular references when we get the resource from the library.

[thomaspoignant]

Hey @blairlunceford thanks for your report, I will release a version 0.8.0 today containing the fix for this issue.