Reproduction steps:
1. Open the user's project "Test.zip"
2. Select `Assets/Scripts/TestScript.nani` asset
3. In the Inspector window edit the first line (change "1" to anything else)
4. Press "Apply" button
Expected result: Asset is saved without warnings.
Actual result: A "'' does not exist" warning is logged.
Reproducible with: 2021.2.0b8, 2021.2.4f1, 2022.1.0a3, 2022.1.0a17
Not reproducible with: 2019.4.3f1, 2019.4.33f1, 2020.3.23f1, 2021.1.0a5, 2021.1.28f1, 2021.2.0b1, 2021.2.0b7, 2022.1.0a2
Couldn't test with: 2019.4.2f1, 2021.1.0a4, 2021.2.0a15 (losing the package when converting the project to these versions)
Notes:
- Couldn't test on some versions and reproductible on all the other versions with macOS (no not reproductible with versions)