Follow up: Check array type as well

addon/-private/validated-changeset.ts

@@ -865,7 +865,7 @@ export class BufferedChangeset implements IChangeset {
         // requested key is the top most nested property and we have changes in of the properties, we need to
         // merge the original model data with the changes to have the complete object.
         // eg. model = { user: { name: 'not changed', email: '[email protected]'} }
-        if (isObject(content[baseKey]) && !isEmberDataObject(content[baseKey])) {
+        if (!Array.isArray(result) && isObject(content[baseKey]) && !isEmberDataObject(content[baseKey])) {
           let data: Record<string, any> = {}
           Object.keys(content[baseKey]).forEach(k => {
             data[k] = this.getDeep(content, `${baseKey}.${k}`)

tests/dummy/app/components/changeset-form.ts

@@ -5,6 +5,7 @@ import Changeset from 'ember-changeset'
 export default class ChangesetForm extends Component {
   model = {
     user: {
+      aliases: ['someone'],
       name: 'someone',
       email: 'something'
     },

tests/unit/changeset-test.js

@@ -296,6 +296,20 @@ module('Unit | Utility | changeset', function(hooks) {
     assert.equal(result, undefined, 'should proxy to change');
   });
 
+  test('#get returns change that is has undefined as value', async function(assert) {
+    set(dummyModel, 'name', 'Bob');
+    set(dummyModel, 'creds', ['burgers']);
+    let dummyChangeset = new Changeset(dummyModel);
+    set(dummyChangeset, 'name', 'Burdger');
+
+    assert.equal(get(dummyChangeset, 'name'), 'Burdger', 'should proxy name to change');
+    assert.deepEqual(get(dummyChangeset, 'creds'), ['burgers'], 'should proxy creds to change');
+
+    set(dummyChangeset, 'creds', ['fries']);
+    assert.equal(get(dummyChangeset, 'name'), 'Burdger', 'should proxy name to change');
+    assert.deepEqual(get(dummyChangeset, 'creds'), ['fries'], 'should proxy creds to change after change');
+  });
+
   test('nested objects will return correct values', async function(assert) {
     set(dummyModel, 'org', {
       asia: { sg: '_initial' },  // for the sake of disambiguating nulls