xhci: crash in Controller::EventRing::processEvent

While testing the nightly image built at 2022-01-10T13:43:25 on my computer (H81M, i5-4690K) I ran into this crash in Controller::EventRing::processEvent on this line:

managarm/drivers/usb/hcds/xhci/src/main.cpp

Line 512 in d1d5afe

transferEv->event = ev;

It did successfully mount the USB disk I was booting off, I don't know what else I can provide, so here's some lspci logs capturing my XHCI controller, for a reference of my hardware:

00:14.0 USB controller: Intel Corporation 8 Series/C220 Series Chipset Family USB xHCI (rev 05) (prog-if 30 [XHCI])
	Subsystem: ASRock Incorporation Device 8c31
	Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx+
	Status: Cap+ 66MHz- UDF- FastB2B+ ParErr- DEVSEL=medium >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
	Latency: 0
	Interrupt: pin A routed to IRQ 29
	Region 0: Memory at f3200000 (64-bit, non-prefetchable) [size=64K]
	Capabilities: [70] Power Management version 2
		Flags: PMEClk- DSI- D1- D2- AuxCurrent=375mA PME(D0-,D1-,D2-,D3hot+,D3cold+)
		Status: D0 NoSoftRst+ PME-Enable- DSel=0 DScale=0 PME-
	Capabilities: [80] MSI: Enable+ Count=1/8 Maskable- 64bit+
		Address: 00000000fee002f8  Data: 0000
	Kernel driver in use: xhci_hcd
	Kernel modules: xhci_pci