Getter doesn't work on a nested single subdocument

[nathan-knight]

I think this was introduced by #43
I have a subdocument that is transformed by the getter into a single object that should be assigned to the original document:

{
  _id: false,
  type: {
    amount: {
      type: mongoose.Types.Decimal128,
      required: true,
    },
    currency: {
      type: String,
      required: true,
    },
  },

  set: transformCurrencyToDbStructure,
  get: transformCurrencyFromDbStructure,
}

This worked before on 2.0.1 but after updating to 2.2.1 it just returns the original subdocument without applying the getter.

mongoose-lean-getters/index.js

Line 121 in 9fcb880

applyGettersToDoc.call(this, schematype.schema, val);

Upon further investigation, it reaches this point and then tries to apply getters to the fields of the subdocument (passing along the transformed subdocument which is now a totally different structure) and then discards the transformed value (val) instead of assigning it to the document.

Locally I've patched it to do mpath.set(path, val, doc); in this case too which has resolved it but I am not certain whether this may have undesired side effects. I can put up a PR for this.