Steps to reproduce:
1. Create a new project
2. Switch the platform to iOS and create a build
3. Start the build again and try to overwrite the previous build (build in the same folder)
4. When prompted if you want to overwrite the current build, click "Cancel"
5. Click "Build" again

Expected result: Unity prompts the same OS windows again, giving you the option to build again
Actual results: Unity hangs and needs to be force quit

Reproducible with: 2018.4.31f1, 2019.4.19f1, 2020.2.0a1, 2020.2.0a21, 2021.1.0a1, 2021.1.0a2
Not reproducible with: 2020.2.3f1, 2021.1.0a3, 2021.1.0b5, 2021.2.0a3 (different OS options are given of creating a folder which might be affecting reproduction)

Notes:
- Reproducible with: macOS 11.0.1 (20B50), 11.1
- Does not reproduce building Mac standalone or Android (likely due to standalone and android building to a single file and not a folder)
- Does not reproduce on 10.15.7 Catalina