After running fuzzer, noticing some panics around index access.
$ nix develop .#fuzz --command cargo fuzz run insert fuzz/artifacts/insert/crash-9b97ed8b7393055832ecd6a6e6542e962c494766
...
thread '<unnamed>' panicked at src/parts.rs:86:29:
index out of bounds: the len is 9 but the index is 9
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
==27406== ERROR: libFuzzer: deadly signal
After running fuzzer, noticing some panics around index access.