Steps to reproduce:
1. Open the user attached project "fep.zip"
2. Open the "TestStackerCrane" Scene in the Assets folder
3. Enter "StackerCraneStateIdleHandler" in the Projects window toolbar's search field and open the returned file with Visual Studio
4. Set a breakpoint on the 135 line of "StackerCraneStateIdleHandler.cs" file
5. In Visual Studio select Attach to Unity and Play
6. In Visual Studio open the Locals window by pressing Ctrl + Alt + V > A
7. In the Locals window navigate to: this > base > Lhds > [0] > Positions > [0] and observe that the variable "StackerMission" is null
8. Remove the breakpoint set in step 2 and press Continue in Visual Studio
9. In Editor open Window > Analysis > Memory Profiler
10. In Memory Profiler window press Capture New Snapshot
11. In Visual Studio set a breakpoint on the 135 line of "StackerCraneStateIdleHandler.cs" file
12. When the breakpoint hits, repeat step 7
13. Observe the value of "StackerMission"

Expected result: the value of "StackerMission" is null
Actual result: the value of "StackerMission" is an empty object

Reproducible with: 2019.4.34f1, 2020.3.25f1
Couldn't test with: 2021.27f1, 2022.1.0b2 due to compilation errors after upgrading the project