otexplorer: crash on arial.ttf

```
x cargo run --quiet --release --bin otexplorer -- C:\Windows\Fonts\arial.ttf > a.txt
thread 'main' panicked at 'assertion failed: `(left == right)`
left: `7`,
right: `0`', otexplorer\src\print.rs:33:17
stack backtrace:
0: std::panicking::begin_panic_handler
at /rustc/fc594f15669680fa70d255faec3ca3fb507c3405/library\std\src\panicking.rs:575
1: core::panicking::panic_fmt
at /rustc/fc594f15669680fa70d255faec3ca3fb507c3405/library\core\src\panicking.rs:64
2: core::fmt::Arguments::new_v1
at /rustc/fc594f15669680fa70d255faec3ca3fb507c3405/library\core\src\fmt\mod.rs:398
3: core::panicking::assert_failed_inner
at /rustc/fc594f15669680fa70d255faec3ca3fb507c3405/library\core\src\panicking.rs:245
4: core::panicking::assert_failed
5: std::io::Write::write_all
6: alloc::alloc::box_free
7: otexplorer::print::PrettyPrinter::print_field
8: otexplorer::print::PrettyPrinter::print_root_table
9: otexplorer::print::PrettyPrinter::print_field
10: otexplorer::print::PrettyPrinter::print_root_table
11: otexplorer::print::PrettyPrinter::print_field
12: otexplorer::print::PrettyPrinter::print_root_table
13: otexplorer::print::PrettyPrinter::print_root_table
14: otexplorer::fancy_print_table
15: ::is_write_vectored
16: read_fonts::traversal::SomeArray::is_empty
17: std::rt::lang_start::{{closure}}
18: core::ops::function::impls::impl$2::call_once
at /rustc/fc594f15669680fa70d255faec3ca3fb507c3405/library\core\src\ops\function.rs:606
19: std::panicking::try::do_call
at /rustc/fc594f15669680fa70d255faec3ca3fb507c3405/library\std\src\panicking.rs:483
20: std::panicking::try
at /rustc/fc594f15669680fa70d255faec3ca3fb507c3405/library\std\src\panicking.rs:447
21: std::panic::catch_unwind
at /rustc/fc594f15669680fa70d255faec3ca3fb507c3405/library\std\src\panic.rs:137
22: std::rt::lang_start_internal::closure$2
at /rustc/fc594f15669680fa70d255faec3ca3fb507c3405/library\std\src\rt.rs:148
23: std::panicking::try::do_call
at /rustc/fc594f15669680fa70d255faec3ca3fb507c3405/library\std\src\panicking.rs:483
24: std::panicking::try
at /rustc/fc594f15669680fa70d255faec3ca3fb507c3405/library\std\src\panicking.rs:447
25: std::panic::catch_unwind
at /rustc/fc594f15669680fa70d255faec3ca3fb507c3405/library\std\src\panic.rs:137
26: std::rt::lang_start_internal
at /rustc/fc594f15669680fa70d255faec3ca3fb507c3405/library\std\src\rt.rs:148
27: main
28: invoke_main
at D:\a\_work\1\s\src\vctools\crt\vcstartup\src\startup\exe_common.inl:78
29: __scrt_common_main_seh
at D:\a\_work\1\s\src\vctools\crt\vcstartup\src\startup\exe_common.inl:288
30: BaseThreadInitThunk
31: RtlUserThreadStart
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
```