How to reproduce:
1. Create a new URP project
2. Go to User Preferences -> Shader Graph 
3. Try set the Preview Variant Limit to a negative value

Expected results: It is not possible to set Preview Variant Limit to a negative number
Actual results: It is possible to set the Preview Variant Limit to a negative number which results in errors in the Console

Reproducible with: 2021.3.40f1, 2022.3.38f1, 6000.0.11f1

Reproducible on: macOS Sonoma 14.5
Not reproducible on: No other environment tested

Full error: Error in Shader Graph Assets/New Shader Graph.shadergraph: Graph is generating too many variants. Either delete Keywords, reduce Keyword variants or increase the Shader Variant Limit in Preferences > Shader Graph.
UnityEditor.EditorApplication:Internal_CallUpdateFunctions () (at /Users/bokken/build/output/unity/unity/Editor/Mono/EditorApplication.cs:384)