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

goroutine 291 [running]:
panic({0x11bd0a0, 0xc0004aa030})
	GOROOT/src/runtime/panic.go:1147 +0x3a8 fp=0xc00044b1e8 sp=0xc00044b128 pc=0x435148
runtime.goPanicIndex(0xffffffffffffffff, 0x0)
	GOROOT/src/runtime/panic.go:90 +0x75 fp=0xc00044b228 sp=0xc00044b1e8 pc=0x4324d5
gvisor.dev/gvisor/pkg/sentry/fsimpl/tmpfs.parseSize({0x0, 0xc0009082d0})
	pkg/sentry/fsimpl/tmpfs/tmpfs.go:951 +0x14c fp=0xc00044b260 sp=0xc00044b228 pc=0x8d858c
gvisor.dev/gvisor/pkg/sentry/fsimpl/tmpfs.FilesystemType.GetFilesystem({}, {0x146bf60, 0xc0004aca80}, 0xc00053cfc0, 0xc00047e3c0, {0xc0005521f0, 0xc00044b528}, {{0xc0005de600, 0x4}, {0x0, ...}})
	pkg/sentry/fsimpl/tmpfs/tmpfs.go:205 +0x5db fp=0xc00044b4f0 sp=0xc00044b260 pc=0x8d53bb
gvisor.dev/gvisor/pkg/sentry/fsimpl/tmpfs.(*FilesystemType).GetFilesystem(0x1ef7fe0, {0x146bf60, 0xc0004aca80}, 0xc00044b5a8, 0xc00044b5a8, {0xc0005de400, 0xc0004bd800}, {{0xc0005de600, 0x4}, {0x0, ...}})
	<autogenerated>:1 +0x8c fp=0xc00044b550 sp=0xc00044b4f0 pc=0x8de86c
gvisor.dev/gvisor/pkg/sentry/vfs.(*VirtualFilesystem).MountDisconnected(0x20003e40, {0x146bf60, 0xc0004aca80}, 0xc0004bd800, {0xc0005de400, 0x8}, {0xc0005de300, 0xc00044b678}, 0xc00044b7c0)
	pkg/sentry/vfs/mount.go:200 +0xe3 fp=0xc00044b5c8 sp=0xc00044b550 pc=0x773423
gvisor.dev/gvisor/pkg/sentry/vfs.(*VirtualFilesystem).MountAt(0xc0002c4400, {0x146bf60, 0xc0004aca80}, 0xc0005de500, {0xc0005de400, 0x1}, 0x0, {0xc0005de300, 0x1}, 0xc00044b7c0)
	pkg/sentry/vfs/mount.go:272 +0x8b fp=0xc00044b688 sp=0xc00044b5c8 pc=0x77384b
gvisor.dev/gvisor/pkg/sentry/syscalls/linux/vfs2.Mount(0xc0004aca80, {{0x20003d40}, {0x20003d80}, {0x20003dc0}, {0x0}, {0x20003e00}, {0x0}})
	pkg/sentry/syscalls/linux/vfs2/mount.go:112 +0x5cf fp=0xc00044b8a8 sp=0xc00044b688 pc=0xe17d4f
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).executeSyscall(0xc0004aca80, 0xa5, {{0x20003d40}, {0x20003d80}, {0x20003dc0}, {0x0}, {0x20003e00}, {0x0}})
	pkg/sentry/kernel/task_syscall.go:142 +0x825 fp=0xc00044bcb0 sp=0xc00044b8a8 pc=0x9b74c5
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscallInvoke(0xc0004aca80, 0x0, {{0x20003d40}, {0x20003d80}, {0x20003dc0}, {0x0}, {0x20003e00}, {0x0}})
	pkg/sentry/kernel/task_syscall.go:322 +0x4d fp=0xc00044bd20 sp=0xc00044bcb0 pc=0x9b87ed
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscallEnter(0xc000aa6680, 0xc0002d00f0, {{0x20003d40}, {0x20003d80}, {0x20003dc0}, {0x0}, {0x20003e00}, {0x0}})
	pkg/sentry/kernel/task_syscall.go:282 +0x65 fp=0xc00044bd80 sp=0xc00044bd20 pc=0x9b84a5
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscall(0xc0004aca80)
	pkg/sentry/kernel/task_syscall.go:257 +0x31a fp=0xc00044be48 sp=0xc00044bd80 pc=0x9b81da
gvisor.dev/gvisor/pkg/sentry/kernel.(*runApp).execute(0xc0001c2380, 0xc0004aca80)
	pkg/sentry/kernel/task_run.go:247 +0xe5e fp=0xc00044bf70 sp=0xc00044be48 pc=0x9ac13e
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).run(0xc0004aca80)
	pkg/sentry/kernel/task_run.go:90 +0x1a2 fp=0xc00044bfc8 sp=0xc00044bf70 pc=0x9aac82
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).Start·dwrap·239()
	pkg/sentry/kernel/task_start.go:363 +0x26 fp=0xc00044bfe0 sp=0xc00044bfc8 pc=0x9b5c06
runtime.goexit()
	src/runtime/asm_amd64.s:1581 +0x1 fp=0xc00044bfe8 sp=0xc00044bfe0 pc=0x4692a1
created by gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).Start
	pkg/sentry/kernel/task_start.go:363 +0xe7