How to reproduce:
1. Open the attached project "Bug.zip"
2. Open "Boot" Scene
3. Open Automated test window ("Support > Automated test window" in the Menu items)
4. Click Start in the custom Automated test window

Expected result: Editor doesn't crash after recompiling a script
Actual result: Editor sometimes crashes after recompiling a script

Reproducible with: 2020.3.19f1, 2021.1.23f1
Could not test with: 2019.4.30f1 (project didn't load), 2021.2.0b14, 2022.1.0a10 (Internal build system error. Backend exited with code 1)

macOS Stacktrace:
#0 0x0000010a20347d in SerializableManagedRefsUtilities::BackupAndDeflateAll(DomainReloadingData&)
#1 0x0000010a1130de in MonoManager::BeginReloadAssembly(DomainReloadingData&)
#2 0x0000010a111bc0 in MonoManager::ReloadAssembly()
#3 0x0000010b644680 in ReloadAllUsedAssemblies()
#4 0x0000010ae02e5f in Application::TickTimer()
#5 0x0000010d062bfc in -[EditorApplication TickTimer]
#6 0x007fff2144a50f in __NSFireTimer
#7 0x007fff2069690d in __CFRUNLOOP_IS_CALLING_OUT_TO_A_TIMER_CALLBACK_FUNCTION__
#8 0x007fff206963e8 in __CFRunLoopDoTimer
#9 0x007fff20695f42 in __CFRunLoopDoTimers
#10 0x007fff2067c57f in __CFRunLoopRun
#11 0x007fff2067b6ce in CFRunLoopRunSpecific
#12 0x007fff28903630 in RunCurrentEventLoopInMode
#13 0x007fff2890342c in ReceiveNextEventCommon
#14 0x007fff2890314f in _BlockUntilNextEventMatchingListInModeWithFilter
#15 0x007fff22e9b9b1 in _DPSNextEvent
#16 0x007fff22e9a177 in -[NSApplication(NSEvent) _nextEventMatchingEventMask:untilDate:inMode:dequeue:]
#17 0x007fff22e8c68a in -[NSApplication run]
#18 0x007fff22e6096f in NSApplicationMain
#19 0x0000010d09ce79 in EditorMain(int, char const**)
#20 0x0000010d09d0a9 in main
#21 0x007fff205a0621 in start