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

goroutine 323 [running]:
panic({0x1933300, 0xc0007c6210})
	GOROOT/src/runtime/panic.go:1147 +0x3a8 fp=0xc00092ccb0 sp=0xc00092cbf0 pc=0x437c88
runtime.goPanicIndex(0xffffffffffffffff, 0x0)
	GOROOT/src/runtime/panic.go:90 +0x75 fp=0xc00092ccf0 sp=0xc00092ccb0 pc=0x435015
gvisor.dev/gvisor/pkg/sentry/fsimpl/tmpfs.parseSize({0x0, 0x0})
	pkg/sentry/fsimpl/tmpfs/tmpfs.go:951 +0x17a fp=0xc00092cd40 sp=0xc00092ccf0 pc=0xbd199a
gvisor.dev/gvisor/pkg/sentry/fsimpl/tmpfs.FilesystemType.GetFilesystem({}, {0x1d09ee0, 0xc0007b8a80}, 0x0, 0xc0007b61e0, {0xc0003be458, 0xc00041cc30}, {{0xc00058cb00, 0x4}, {0x0, ...}})
	pkg/sentry/fsimpl/tmpfs/tmpfs.go:205 +0x78f fp=0xc00092d058 sp=0xc00092cd40 pc=0xbccc2f
gvisor.dev/gvisor/pkg/sentry/fsimpl/tmpfs.(*FilesystemType).GetFilesystem(0x32877b0, {0x1d09ee0, 0xc0007b8a80}, 0x0, 0x470e45, {0xc00058c900, 0x8}, {{0xc00058cb00, 0x4}, {0x0, ...}})
	<autogenerated>:1 +0xe8 fp=0xc00092d0e8 sp=0xc00092d058 pc=0xbda0a8
gvisor.dev/gvisor/pkg/sentry/vfs.(*VirtualFilesystem).MountDisconnected(0xc00092d190, {0x1d09ee0, 0xc0007b8a80}, 0x0, {0xc00058c900, 0x8}, {0xc00058c800, 0x5}, 0xc00092d468)
	pkg/sentry/vfs/mount.go:200 +0x1b8 fp=0xc00092d1a8 sp=0xc00092d0e8 pc=0x9a58b8
gvisor.dev/gvisor/pkg/sentry/vfs.(*VirtualFilesystem).MountAt(0xc000418400, {0x1d09ee0, 0xc0007b8a80}, 0xc00058ca00, {0xc00058c900, 0x8}, 0x0, {0xc00058c800, 0x5}, 0xc00092d468)
	pkg/sentry/vfs/mount.go:272 +0xdd fp=0xc00092d2b0 sp=0xc00092d1a8 pc=0x9a5efd
gvisor.dev/gvisor/pkg/sentry/syscalls/linux/vfs2.Mount(0xc0007b8a80, {{0x20003d40}, {0x20003d80}, {0x20003dc0}, {0x0}, {0x20003e00}, {0x0}})
	pkg/sentry/syscalls/linux/vfs2/mount.go:112 +0x7b1 fp=0xc00092d548 sp=0xc00092d2b0 pc=0x1391f51
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).executeSyscall(0xc0007b8a80, 0xa5, {{0x20003d40}, {0x20003d80}, {0x20003dc0}, {0x0}, {0x20003e00}, {0x0}})
	pkg/sentry/kernel/task_syscall.go:142 +0x9d8 fp=0xc00092da90 sp=0xc00092d548 pc=0xd337f8
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscallInvoke(0xc0007b8a80, 0x46f779, {{0x20003d40}, {0x20003d80}, {0x20003dc0}, {0x0}, {0x20003e00}, {0x0}})
	pkg/sentry/kernel/task_syscall.go:322 +0x6a fp=0xc00092db18 sp=0xc00092da90 pc=0xd353ea
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscallEnter(0xc0007ae0f0, 0x46fc2c, {{0x20003d40}, {0x20003d80}, {0x20003dc0}, {0x0}, {0x20003e00}, {0x0}})
	pkg/sentry/kernel/task_syscall.go:282 +0x8f fp=0xc00092db90 sp=0xc00092db18 pc=0xd34e6f
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscall(0xc0007b8a80)
	pkg/sentry/kernel/task_syscall.go:257 +0x3e7 fp=0xc00092dc98 sp=0xc00092db90 pc=0xd34a87
gvisor.dev/gvisor/pkg/sentry/kernel.(*runApp).execute(0xc0007b8a80, 0xc0007b8a80)
	pkg/sentry/kernel/task_run.go:247 +0x16b8 fp=0xc00092ded0 sp=0xc00092dc98 pc=0xd1feb8
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).run(0xc0007b8a80)
	pkg/sentry/kernel/task_run.go:90 +0x35b fp=0xc00092dfc0 sp=0xc00092ded0 pc=0xd1ddfb
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).Start·dwrap·239()
	pkg/sentry/kernel/task_start.go:363 +0x3a fp=0xc00092dfe0 sp=0xc00092dfc0 pc=0xd312fa
runtime.goexit()
	src/runtime/asm_amd64.s:1581 +0x1 fp=0xc00092dfe8 sp=0xc00092dfe0 pc=0x46e001
created by gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).Start
	pkg/sentry/kernel/task_start.go:363 +0x191