How to reproduce:
1. Open the attached project (case_1322064-InvalidPath)
2. Observe that the 'folder ' directory in the assets has a trailing space
3. Click Assets/Export Package
4. Try to import the package to a new project

Expected result: Unity detects the space at the end of the directory and does not allow the export
Actual result: Unity exports the package

Reproducible with: 2019.4.23f1, 2020.3.2f1, 2021.1.2f1, 2021.2.0a10
Could not test with: 2018.4.33f1 (Unity ignores the directory)

Notes:
1. *"<>?| are symbols only allowed on MacOS. If a package with these symbols was exported on Mac and imported on Windows Unity should strip them