Mojave kernel panic related to Slack?

Macbook Pro 15″ mid-2015, MacOs Mojave 10.14.6 (18G7016), 2 external displays (HDMI and Thunderbolt-to-HDMI adaptor)

On 2 consecutive days I’ve had kernel panics that have restarted my mac. IIRC, the apps that were open both times were:

  • Slack
  • Webstorm
  • Chrome
  • Outlook
  • iTerm2
  • Apple mail

The 2 logs in my Diagnostic Reports folder both have the text:

possible cause: unlocking an unlocked mutex or
spinlock"@/BuildRoot/Library/Caches/com.apple.xbs/Sources/xnu/xnu-
4903.278.51/osfmk/kern/sched_prim.c:2420

and

BSD process name corresponding to current thread: Slack

I also ran an EtreCheck report but it didn’t mention Slack in it’s possible causes (report summary attached). Any help in interpreting appreciated!

Diagnostics Information (past 7-30 days):
    2021-07-14 12:15:09 Kernel Panic (2 times)
        Details:
            panic(cpu 2 caller 0xffffff8000bccc3f): "thread_invoke: preemption_lev
            el -1, possible cause: unlocking an unlocked mutex or spinlock"@/Build
            Root/Library/Caches/com.apple.xbs/Sources/xnu/xnu-4903.278.51/osfmk/ke
            rn/sched_prim.c:2420
        3rd party kernel extensions:
            com.Cycling74.driver.Soundflower
            com.avast.FileShield
            com.avast.PacketForwarder
            com.intel.kext.intelhaxm
            com.logmein.hamachi
            com.motu.driver.FireWireAudio
            com.paceap.kext.pacesupport.snowleopard
            org.virtualbox.kext.VBoxDrv
            org.virtualbox.kext.VBoxNetAdp
            org.virtualbox.kext.VBoxNetFlt
            org.virtualbox.kext.VBoxUSB

    2021-07-13 01:01:52 signpost_reporter - High CPU Use
        Executable: /usr/libexec/signpost_reporter

    2021-07-08 14:28:41 mdsync - High CPU Use (2 times)
        Executable: /System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks/Metadata.framework/Versions/A/Support/mdsync