Steps to reproduce:
1. Create new Unity project using Universal 3D Template
2. Create InputField GameObject in the Hierarchy window
3. Import TMP Essentials
4. Expand Canvas > InputField (TMP) > Text Area
5. Select Placeholder GO
6. Observe the Console window

Actual results: "NullReferenceException" errors are continuously spammed in the Console window when the Placeholder child object of Canvas > InputField (TMP) > Text Area is selected

Expected results: No errors are thrown in the Console when selecting the Placeholder object in the Hierarchy

Reproducible with versions: 6000.6.0a1 (7dc703ab9bd8), 6000.6.0a7

Not reproducible with versions: 6000.5.0a7, 6000.5.0b12 (6949ce73bc35)

Tested on (OS): Windows 11, macOS Tahoe 26.4.1

NullReferenceException: Object reference not set to an instance of an object
TMPro.MaterialReference..ctor (System.Int32 index, TMPro.TMP_FontAsset fontAsset, TMPro.TMP_SpriteAsset spriteAsset, UnityEngine.Material material, System.Single padding) (at ./Library/PackageCache/com.unity.ugui@6d075bb4592c/Runtime/TMP/MaterialReferenceManager.cs:596)
TMPro.TextMeshProUGUI.SetArraySizes (TMPro.TMP_Text+TextProcessingElement[] textProcessingArray) (at ./Library/PackageCache/com.unity.ugui@6d075bb4592c/Runtime/TMP/TextMeshProUGUI.cs:1724)
TMPro.TMP_Text.ParseInputText () (at ./Library/PackageCache/com.unity.ugui@6d075bb4592c/Runtime/TMP/TMP_Text.cs:2090)
TMPro.TMP_Text.GetPreferredWidth () (at ./Library/PackageCache/com.unity.ugui@6d075bb4592c/Runtime/TMP/TMP_Text.cs:3882)
TMPro.TMP_Text.get_preferredWidth () (at ./Library/PackageCache/com.unity.ugui@6d075bb4592c/Runtime/TMP/TMP_Text.cs:1556)
UnityEditor.Events.LayoutPropertiesPreview+<>c.<OnPreviewGUI>b__8_4 (UnityEngine.UI.ILayoutElement e) (at ./Library/PackageCache/com.unity.ugui@6d075bb4592c/Editor/UGUI/UI/LayoutPropertiesPreview.cs:101)