The Editor crashes when saving a custom package’s manifest with a name that has an upper case letter

Steps to reproduce:

1. Create a new Unity project using the Universal 3D template
2. Open the Package Manager window (Window > Package Management > Package Manager)
3. Create a custom package named "asd" by pressing the "+" button in the Package Manager window
4. Select the "asd" package in the Package Manager
5. Click the "Edit" button in the Inspector window
6. Change the "Name" field to "Asd"
7. Click anywhere in the Project window
8. Click the "Save" button
9. Click the "Update Name" button
10. Observe the Editor

Actual results: The Editor crashes

Expected results: There is a field validation that does not let user save a name with an upper case letter or the Editor does not crash

Reproducible with versions: 6000.4.0a1, 6000.4.3f1 

Not reproducible with versions: 6000.3.13f1, 6000.5.0b4, 6000.6.0a2

Can’t test with versions: 6000.0.73f1 (due to no custom package creation feature)

Tested on (OS): MacOS Silicon Tahoe 26.3, Ubuntu 24.04

Notes:

• Seems to only affect the 6.4 stream

First few lines of stack trace:

#0  0x000001038cfb9c in WriteObjectToVector(Object const&, core::vector<unsigned char, core::allocator<unsigned char, 0ul>>&, TransferInstructionFlags, BuildTargetSelection)
#1  0x000001008245b0 in CreateOrReloadInspectorCopy(EntityId, Object)*
#2  0x00000101d66774 in AssetImporterEditor_CUSTOM_CreateOrReloadInspectorCopy(EntityId const&, void)*
#3  0x0000034c319d10 in  (wrapper managed-to-native) UnityEditor.AssetImporters.AssetImporterEditor:CreateOrReloadInspectorCopy_Injected (UnityEngine.EntityId&,intptr) [

{0xa0e1d3428}

+ 0x68]  (0x34c319ca8 0x34c319d74) [0x160dc2a80 - Unity Child Domain]
#4  0x0000034c319a44 in  UnityEditor.AssetImporters.AssetImporterEditor:CreateOrReloadInspectorCopy (UnityEngine.EntityId,UnityEditor.Editor) [

{0xa0709c250}

+ 0x7c]  (0x34c3199c8 0x34c319b98) [0x160dc2a80 - Unity Child Domain]
#5  0x0000034c318594 in  UnityEditor.AssetImporters.AssetImporterEditor:InitializeUnsavedChangesCache () [

{0xa0709c548}

+ 0x1b4] [/Users/bokken/build/output/unity/unity/Modules/AssetPipelineEditor/ImportSettings/AssetImporterEditor.cs :: 213u] (0x34c3183e0 0x34c3189c8) [0x160dc2a80 - Unity Child Domain]