Steps to reproduce:
1. Create new Unity project
2. Open Font Asset Creator window (Window > Text > Font Asset Creator)
3. In Source Font select built-in font (Inter-Italic)
4. Press "Generate Font Atlas" button
5. When generated, press "Save as..."
6. Observe the Console window
 

Actual results: Saving generated font throws errors in the Console window
Expected results: No errors are thrown when saving generated font

Reproducible with versions: 6000.2.6f1, 6000.3.0b2
Can’t test with versions: 6000.0.58f1 (UUM-95779)

Tested on (OS): Windows 11 (Alienware m15 R4)

Errors:
1. Couldn't create asset file!
UnityEngine.GUIUtility:ProcessEvent (int,intptr,bool&)

2. GUI Error: Invalid GUILayout state in FontAssetCreatorWindow view. Verify that all layout Begin/End calls match
UnityEngine.GUIUtility:ProcessEvent (int,intptr,bool&)

3. UnityException: Creating asset at path Library/Inter-Italic.asset failed.
UnityEditor.AssetDatabase.CreateAsset (UnityEngine.Object asset, System.String path) (at <903ac5666bcd49cc9340cf587389e973>:0)
UnityEditor.TextCore.Text.FontAssetCreatorWindow.Save_Bitmap_FontAsset (System.String filePath) (at <42b76e62d57e42d0889dfae69d2e9ddf>:0)
UnityEditor.TextCore.Text.FontAssetCreatorWindow.SaveNewFontAsset (UnityEngine.Object sourceObject) (at <42b76e62d57e42d0889dfae69d2e9ddf>:0)