panic: runtime error: index out of range [-1]

goroutine 165 [running]:
panic({0x1a666e0, 0xc000452258})
	GOROOT/src/runtime/panic.go:1147 +0x3a8 fp=0xc00088ed98 sp=0xc00088ecd8 pc=0x437c88
runtime.goPanicIndex(0xffffffffffffffff, 0x0)
	GOROOT/src/runtime/panic.go:90 +0x75 fp=0xc00088edd8 sp=0xc00088ed98 pc=0x435015
gvisor.dev/gvisor/pkg/sentry/fsimpl/tmpfs.parseSize({0x0, 0x0})
	pkg/sentry/fsimpl/tmpfs/tmpfs.go:951 +0x26c fp=0xc00088ee30 sp=0xc00088edd8 pc=0xc5f66c
gvisor.dev/gvisor/pkg/sentry/fsimpl/tmpfs.FilesystemType.GetFilesystem({}, {0x1d93b00, 0xc0005de000}, 0x0, 0xc0007b63c0, {0xc0001c02a0, 0x470e45}, {{0xc0001d4600, 0x4}, {0x0, ...}})
	pkg/sentry/fsimpl/tmpfs/tmpfs.go:205 +0xa45 fp=0xc00088f120 sp=0xc00088ee30 pc=0xc59a25
gvisor.dev/gvisor/pkg/sentry/fsimpl/tmpfs.(*FilesystemType).GetFilesystem(0x3472b70, {0x1d93b00, 0xc0005de000}, 0x1, 0x4455, {0xc0001d4400, 0x8}, {{0xc0001d4600, 0x4}, {0x0, ...}})
	<autogenerated>:1 +0xe8 fp=0xc00088f1b0 sp=0xc00088f120 pc=0xc685e8
gvisor.dev/gvisor/pkg/sentry/vfs.(*VirtualFilesystem).MountDisconnected(0x0, {0x1d93b00, 0xc0005de000}, 0x0, {0xc0001d4400, 0x8}, {0xc0001d4300, 0x5}, 0xc00088f568)
	pkg/sentry/vfs/mount.go:200 +0x1db fp=0xc00088f280 sp=0xc00088f1b0 pc=0x9ec93b
gvisor.dev/gvisor/pkg/sentry/vfs.(*VirtualFilesystem).MountAt(0xc000459b00, {0x1d93b00, 0xc0005de000}, 0xc0001d4500, {0xc0001d4400, 0x8}, 0x0, {0xc0001d4300, 0x5}, 0xc00088f568)
	pkg/sentry/vfs/mount.go:272 +0xf2 fp=0xc00088f3a8 sp=0xc00088f280 pc=0x9ed052
gvisor.dev/gvisor/pkg/sentry/syscalls/linux/vfs2.Mount(0xc0005de000, {{0x20003d40}, {0x20003d80}, {0x20003dc0}, {0x0}, {0x20003e00}, {0x7f598639de78}})
	pkg/sentry/syscalls/linux/vfs2/mount.go:112 +0x6b8 fp=0xc00088f648 sp=0xc00088f3a8 pc=0x14a9fd8
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).executeSyscall(0xc0005de000, 0xa5, {{0x20003d40}, {0x20003d80}, {0x20003dc0}, {0x0}, {0x20003e00}, {0x7f598639de78}})
	pkg/sentry/kernel/task_syscall.go:142 +0xaf7 fp=0xc00088fa98 sp=0xc00088f648 pc=0xde2337
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscallInvoke(0xc0005de000, 0x1, {{0x20003d40}, {0x20003d80}, {0x20003dc0}, {0x0}, {0x20003e00}, {0x7f598639de78}})
	pkg/sentry/kernel/task_syscall.go:322 +0x8e fp=0xc00088fb28 sp=0xc00088fa98 pc=0xde444e
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscallEnter(0xc0005d8000, 0x1, {{0x20003d40}, {0x20003d80}, {0x20003dc0}, {0x0}, {0x20003e00}, {0x7f598639de78}})
	pkg/sentry/kernel/task_syscall.go:282 +0xc5 fp=0xc00088fba0 sp=0xc00088fb28 pc=0xde3d45
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscall(0xc0005de000)
	pkg/sentry/kernel/task_syscall.go:257 +0x4c7 fp=0xc00088fcb0 sp=0xc00088fba0 pc=0xde3867
gvisor.dev/gvisor/pkg/sentry/kernel.(*runApp).execute(0xc0005de000, 0xc0005de000)
	pkg/sentry/kernel/task_run.go:247 +0x19fc fp=0xc00088fed0 sp=0xc00088fcb0 pc=0xdccebc
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).run(0xc0005de000)
	pkg/sentry/kernel/task_run.go:90 +0x2c2 fp=0xc00088ffc0 sp=0xc00088fed0 pc=0xdcaa82
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).Start·dwrap·239()
	pkg/sentry/kernel/task_start.go:363 +0x3a fp=0xc00088ffe0 sp=0xc00088ffc0 pc=0xddf97a
runtime.goexit()
	src/runtime/asm_amd64.s:1581 +0x1 fp=0xc00088ffe8 sp=0xc00088ffe0 pc=0x46e001
created by gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).Start
	pkg/sentry/kernel/task_start.go:363 +0x1b1