Reproduction steps:
1. Open the “TextFieldNull“ project
2. Open the “TestWindow” window (Tools > TestWindow)
3. Select the text field, input any character, and observe the Console

Expected result: the character is inputted to the text field, and there is no “NullReferenceException” in the Console
Actual result: the character is not inputted to the text field, and there is a “NullReferenceException: Object reference not set to an instance of an object UnityEngine.TextEditingUtilities.ReplaceSelection (System.String replace) (at /Users/bokken/build/output/unity/unity/Modules/IMGUI/TextEditingUtilities.cs:459)“ error in the Console

Reproduced in: 2023.1.0a20, 2023.1.0b5, 2023.2.0a3
Not reproduced in: 2020.3.45f1, 2021.3.19f1, 2022.2.7f1, 2023.1.0a19

Reproduced using: macOS 13.0.1 (Intel), Windows 10 (by the reporter)

Note: not reproduced with “EditorGUILayout.TextField”