How to reproduce:
1. Open or create a project with ProBuilder imported
2. Open the ProBuilder window
3. Using the New Poly Shape tool, place down the base of the shape
4. Try setting the extrude point

Expected result: Able to successfully create the shape
Actual result: Unable to create the shape. “IndexOutOfRangeException: Index was outside the bounds of the array.” errors occur

Reproducible with: 5.1.0 (2021.3.28f1, 2022.3.5f1, 2023.1.4f1, 2023.2.0a23)
Not reproducible with: 5.0.7 (2021.3.28f1, 2022.3.5f1, 2023.1.4f1, 2023.2.0a23)

Reproduced on: macOS (Intel) 13.4.1, Windows 11 (user’s machine)

Note: Cancelling out of the shape creation process and re-selecting the PolyShape in the Hierarchy will show the wireframe of the shape