Reproduction steps:
1. Open the attached “repro_IN-89353“ project
2. Open the “Assets/Scene.unity“ Scene
3. In the Hierarchy, select the “Test“ GameObject
4. In the Inspector, in the “Test Component (Script)“ Component, expand the “Localize Audio List“ dropdown
5. Press the '+' button
6. Observe the Console

Expected result: No errors appear
Actual result: “NullReferenceException: Object reference not set to an instance of an object“ error appears

Reproducible with: 1.0.0-pre.9 (2021.3.47f1), 1.5.3 (2021.3.47f1, 2022.3.55f1, 6000.0.33f1, 6000.1.0a10)

Reproducible on: Windows 10 (22H2), Windows 11 (24H2) (reporter’s environment)
Not reproducible on: No other environments tested

Notes:

* On 2021.3.47f1, after pressing the '+' button, the dropdown UI breaks
* On 2021.3.47f1, on the 1.5.3 version of the Localization package, after pressing the ‘+' button, saving the Scene with “Ctrl + S“ button combination doesn’t work
* According to the reporter, the issue is in the “if (baseType.IsArray) BaseType = baseType.GetElementType().BaseType;” line, which is the 33rd line of the “com.unity.localization@1.5.3\Editor\UI\Localized Reference\LocalizedAssetPropertyDrawer.cs” Script