I'm not sure if this is the right place to put this, so I won't be at all offended if it moves.
I believe that I had hit cmd-U to reflash the generic nano, and that it was writing orange when I hit cmd-Q (aiming for S, but I believe I missed).
The code window at least started shrinking when I was startled by the drive ejection mechanism, and the screen then changed. Then the grey screen about restarting for a problem.
Nothing else save a wired usb keyboard and an external monitor was attached.
It's been years since this machine has crashed (and that was over bad memory), so I suspect that it must have been what I was doing at that point.
I'm posting this not because I need a solution (I can't reproduce it anyway), but as a possible datapoint for someone else's hunt. The hardware report is below.
hawk
Anonymous UUID: 76C9EB9C-8929-C880-0F86-DB09275D0CB6
Mon Mar 11 14:19:54 2019
*** Panic Report ***
panic(cpu 3 caller 0xffffff80276bc02d): "a freed zone element has been modified in zone kalloc.32: expected 0xe4988ed9ea594e86 but found 0xb282c39ca140, bits changed 0xe4983c5b29c5efc6, at offset 0 of 32 in element 0xffffff804e755ae0, cookies 0x3f00112e59f508a8 0x53521186d01f8c1"@/BuildRoot/Library/Caches/com.apple.xbs/Sources/xnu/xnu-4570.71.22/osfmk/kern/zalloc.c:1122
Backtrace (CPU 3), Frame : Return Address
0xffffff9236013910 : 0xffffff802766e1c6
0xffffff9236013960 : 0xffffff8027796a74
0xffffff92360139a0 : 0xffffff8027788d44
0xffffff9236013a10 : 0xffffff80276201e0
0xffffff9236013a30 : 0xffffff802766dc3c
0xffffff9236013b60 : 0xffffff802766d9fc
0xffffff9236013bc0 : 0xffffff80276bc02d
0xffffff9236013c20 : 0xffffff80276bb900
0xffffff9236013c70 : 0xffffff80276ba303
0xffffff9236013da0 : 0xffffff8027679c14
0xffffff9236013e10 : 0xffffff8027b344a2
0xffffff9236013f40 : 0xffffff8027c04248
0xffffff9236013fa0 : 0xffffff80276209c6
BSD process name corresponding to current thread: securityd
Mac OS version:
17G5019
Kernel version:
Darwin Kernel Version 17.7.0: Thu Dec 20 21:47:19 PST 2018; root:xnu-4570.71.22~1/RELEASE_X86_64
Kernel UUID: 4A5298BF-709E-37DF-B7F0-4298065CC266
Kernel slide: 0x0000000027400000
Kernel text base: 0xffffff8027600000
__HIB text base: 0xffffff8027500000
System model name: iMac12,2 (Mac-942B59F58194171B)
System uptime in nanoseconds: 1038711256692899
last loaded kext at 1036965262564340: com.apple.filesystems.apfs 748.51.0 (addr 0xffffff7faad85000, size 999424)
last unloaded kext at 1037068924458833: com.apple.driver.AppleXsanScheme 3 (addr 0xffffff7faad7d000, size 32768)
loaded kexts:
com.wch.usbserial 1
com.apple.driver.AppleBluetoothMultitouch 92
com.apple.driver.AudioAUUC 1.70
com.apple.driver.AppleHWSensor 1.9.5d0
com.apple.driver.AGPM 110.23.37
com.apple.filesystems.autofs 3.0
com.apple.driver.AppleMikeyHIDDriver 131
com.apple.driver.AppleMikeyDriver 281.52
com.apple.AGDCPluginDisplayMetrics 3.20.0
com.apple.driver.AppleUpstreamUserClient 3.6.5
com.apple.driver.AppleHDA 281.52
com.apple.driver.pmtelemetry 1
com.apple.iokit.IOUserEthernet 1.0.1
com.apple.iokit.IOBluetoothSerialManager 6.0.7f12
com.apple.kext.AMDLegacyFramebuffer 1.6.8
com.apple.Dont_Steal_Mac_OS_X 7.0.0
com.apple.kext.AMDRadeonX3000 1.6.8
com.apple.driver.AppleHV 1
com.apple.driver.AppleIntelHD3000Graphics 10.0.4
com.apple.driver.eficheck 1
com.apple.driver.AppleThunderboltIP 3.1.1
com.apple.kext.AMD6000Controller 1.6.8
com.apple.driver.AppleOSXWatchdog 1
com.apple.driver.AppleSMCPDRC 1.0.0
com.apple.driver.AppleIntelSlowAdaptiveClocking 4.0.0
com.apple.driver.AppleLPC 3.1
com.apple.driver.AppleIntelSNBGraphicsFB 10.0.4
com.apple.driver.AppleSMCLMU 211
com.apple.driver.ACPI_SMC_PlatformPlugin 1.0.0
com.apple.driver.AppleBacklight 170.12.6
com.apple.driver.AppleMCCSControl 1.5.5
com.apple.iokit.SCSITaskUserClient 404.30.2
com.apple.driver.AppleIRController 353
com.apple.driver.AppleUSBCardReader 439.70.3
com.apple.AppleFSCompression.AppleFSCompressionTypeDataless 1.0.0d1
com.apple.AppleFSCompression.AppleFSCompressionTypeZlib 1.0.0
com.apple.AppleSystemPolicy 1.0
com.apple.BootCache 40
com.apple.filesystems.hfs.kext 407.50.6
com.apple.driver.AirPort.Atheros40 700.74.5
com.apple.iokit.AppleBCM5701Ethernet 10.3.1
com.apple.driver.AppleFWOHCI 5.5.9
com.apple.driver.AppleAHCIPort 329.50.2
com.apple.driver.AppleRTC 2.0
com.apple.driver.AppleACPIButtons 6.1
com.apple.driver.AppleHPET 1.8
com.apple.driver.AppleSMBIOS 2.1
com.apple.driver.AppleACPIEC 6.1
com.apple.driver.AppleAPIC 1.7
com.apple.driver.AppleIntelCPUPowerManagementClient 220.50.1
com.apple.nke.applicationfirewall 183
com.apple.security.quarantine 3
com.apple.security.TMSafetyNet 8
com.apple.driver.AppleIntelCPUPowerManagement 220.50.1
com.apple.driver.IOBluetoothHIDDriver 6.0.7f12
com.apple.driver.AppleMultitouchDriver 1614.1
com.apple.driver.AppleInputDeviceSupport 1614.11
com.apple.kext.triggers 1.0
com.apple.driver.DspFuncLib 281.52
com.apple.kext.OSvKernDSPLib 526
com.apple.iokit.IOSerialFamily 11
com.apple.iokit.IOAVBFamily 683.1
com.apple.plugin.IOgPTPPlugin 680.15
com.apple.driver.AppleSSE 1.0
com.apple.iokit.IOAcceleratorFamily2 378.26
com.apple.iokit.IOSurface 211.15
com.apple.iokit.IOFireWireIP 2.2.9
com.apple.AppleGPUWrangler 3.20.0
com.apple.driver.AppleHDAController 281.52
com.apple.iokit.IOHDAFamily 281.52
com.apple.iokit.IOAudioFamily 206.5
com.apple.vecLib.kext 1.2.0
com.apple.iokit.IOSlowAdaptiveClockingFamily 1.0.0
com.apple.driver.AppleThunderboltEDMSink 4.1.4
com.apple.driver.AppleSMBusPCI 1.0.14d1
com.apple.kext.AMDLegacySupport 1.6.8
com.apple.driver.IOPlatformPluginLegacy 1.0.0
com.apple.driver.IOPlatformPluginFamily 6.0.0d8
com.apple.AppleGraphicsDeviceControl 3.20.14
com.apple.driver.AppleBacklightExpert 1.1.0
com.apple.iokit.IONDRVSupport 519.21
com.apple.driver.AppleSMBusController 1.0.18d1
com.apple.iokit.IOGraphicsFamily 519.21
com.apple.iokit.IOSCSIMultimediaCommandsDevice 404.30.2
com.apple.iokit.IOBDStorageFamily 1.8
com.apple.iokit.IODVDStorageFamily 1.8
com.apple.iokit.IOCDStorageFamily 1.8
com.apple.iokit.IOAHCISerialATAPI 267.50.1
com.apple.driver.usb.IOUSBHostHIDDevice 1.2
com.apple.iokit.BroadcomBluetoothHostControllerUSBTransport 6.0.7f12
com.apple.iokit.IOBluetoothHostControllerUSBTransport 6.0.7f12
com.apple.iokit.IOBluetoothHostControllerTransport 6.0.7f12
com.apple.iokit.IOBluetoothFamily 6.0.7f12
com.apple.driver.usb.networking 5.0.0
com.apple.driver.usb.AppleUSBHostCompositeDevice 1.2
com.apple.filesystems.hfs.encodings.kext 1
com.apple.driver.usb.AppleUSBHub 1.2
com.apple.driver.AppleThunderboltDPInAdapter 5.5.5
com.apple.driver.AppleThunderboltDPOutAdapter 5.5.5
com.apple.driver.AppleThunderboltDPAdapterFamily 5.5.5
com.apple.driver.AppleThunderboltPCIDownAdapter 2.1.3
com.apple.iokit.IOAHCIBlockStorage 301.40.2
com.apple.iokit.IO80211Family 1200.12.2
com.apple.driver.corecapture 1.0.4
com.apple.driver.AppleThunderboltNHI 4.7.3
com.apple.iokit.IOThunderboltFamily 6.7.9
com.apple.iokit.IOEthernetAVBController 1.1.0
com.apple.driver.mDNSOffloadUserClient 1.0.1b8
com.apple.iokit.IOFireWireFamily 4.7.2
com.apple.driver.usb.AppleUSBHostPacketFilter 1.0
com.apple.iokit.IOAHCIFamily 288
com.apple.driver.usb.AppleUSBEHCIPCI 1.2
com.apple.driver.usb.AppleUSBEHCI 1.2
com.apple.iokit.IOUSBFamily 900.4.1
com.apple.driver.AppleUSBHostMergeProperties 1.2
com.apple.driver.AppleEFINVRAM 2.1
com.apple.driver.AppleEFIRuntime 2.1
com.apple.iokit.IOSMBusFamily 1.1
com.apple.iokit.IOHIDFamily 2.0.0
com.apple.security.sandbox 300.0
com.apple.kext.AppleMatch 1.0.0d1
com.apple.driver.AppleFDEKeyStore 28.30
com.apple.driver.AppleEffaceableStorage 1.0
com.apple.driver.AppleKeyStore 2
com.apple.driver.AppleUSBTDM 439.70.3
com.apple.driver.AppleMobileFileIntegrity 1.0.5
com.apple.iokit.IOUSBMassStorageDriver 140.70.2
com.apple.iokit.IOSCSIBlockCommandsDevice 404.30.2
com.apple.iokit.IOSCSIArchitectureModelFamily 404.30.2
com.apple.driver.AppleCredentialManager 1.0
com.apple.driver.KernelRelayHost 1
com.apple.iokit.IOUSBHostFamily 1.2
com.apple.driver.usb.AppleUSBCommon 1.0
com.apple.driver.AppleBusPowerController 1.0
com.apple.driver.AppleSEPManager 1.0.1
com.apple.driver.IOSlaveProcessor 1
com.apple.driver.DiskImages 480.60.2
com.apple.iokit.IOStorageFamily 2.1
com.apple.iokit.IOReportFamily 31
com.apple.iokit.IOTimeSyncFamily 680.15
com.apple.iokit.IONetworkingFamily 3.4
com.apple.driver.AppleACPIPlatform 6.1
com.apple.driver.AppleSMC 3.1.9
com.apple.iokit.IOPCIFamily 2.9
com.apple.iokit.IOACPIFamily 1.4
com.apple.kec.Libm 1
com.apple.kec.pthread 1
com.apple.kec.corecrypto 1.0
EOF
Unable to gather system configuration information.