Lua specific panic.

OS: Arch Linux x86_64

❯ pacman -Qi harper-git | grep Version
Version : 4232.5c3c66476-1
forgot to add, my editor is neovim

also happens with harper from official repos version 2.1.0, with minimal config just cmd and filetypes = { 'lua' }

steps to reproduce: after fresh reboot open a lua file, lua crashes, markdown and rust doens't
the main thread stack trace from coredumpctl info harper-ls

```
Stack trace of thread 520660:
#0 0x00007fc1be09a29c n/a (libc.so.6 + 0x9a29c)
#1 0x00007fc1be03e7d0 raise (libc.so.6 + 0x3e7d0)
#2 0x00007fc1be025681 abort (libc.so.6 + 0x25681)
#3 0x0000564c604d9e5a n/a (/usr/bin/harper-ls + 0x34c7e5a)
#4 0x0000564c604b26b9 n/a (/usr/bin/harper-ls + 0x34a06b9)
#5 0x0000564c604db1a9 n/a (/usr/bin/harper-ls + 0x34c91a9)
#6 0x0000564c60402309 n/a (/usr/bin/harper-ls + 0x33f0309)
#7 0x0000564c604b26f9 n/a (/usr/bin/harper-ls + 0x34a06f9)
#8 0x0000564c604b210a n/a (/usr/bin/harper-ls + 0x34a010a)
#9 0x0000564c604dad07 n/a (/usr/bin/harper-ls + 0x34c8d07)
#10 0x0000564c604dacb9 n/a (/usr/bin/harper-ls + 0x34c8cb9)
#11 0x0000564c604db1cc n/a (/usr/bin/harper-ls + 0x34c91cc)
#12 0x0000564c5fdbd9eb n/a (/usr/bin/harper-ls + 0x2dab9eb)
#13 0x0000564c5fcde75a n/a (/usr/bin/harper-ls + 0x2ccc75a)
#14 0x0000564c602db020 n/a (/usr/bin/harper-ls + 0x32c9020)
#15 0x0000564c601fdee2 n/a (/usr/bin/harper-ls + 0x31ebee2)
#16 0x0000564c602084ec n/a (/usr/bin/harper-ls + 0x31f64ec)
#17 0x0000564c6022275b n/a (/usr/bin/harper-ls + 0x321075b)
#18 0x0000564c5fce3ed4 n/a (/usr/bin/harper-ls + 0x2cd1ed4)
#19 0x0000564c602f37ae n/a (/usr/bin/harper-ls + 0x32e17ae)
#20 0x0000564c6033db7a n/a (/usr/bin/harper-ls + 0x332bb7a)
#21 0x0000564c603397ab n/a (/usr/bin/harper-ls + 0x33277ab)
#22 0x0000564c603bd1e9 n/a (/usr/bin/harper-ls + 0x33ab1e9)
#23 0x0000564c602fc786 n/a (/usr/bin/harper-ls + 0x32ea786)
#24 0x0000564c603c5829 n/a (/usr/bin/harper-ls + 0x33b3829)
#25 0x00007fc1be027741 n/a (libc.so.6 + 0x27741)
#26 0x00007fc1be027879 __libc_start_main (libc.so.6 + 0x27879)
#27 0x0000564c5fcd8825 n/a (/usr/bin/harper-ls + 0x2cc6825)
```

i hope it helps.

Reproduce the crash with harper-ls from Neovim using the minimal configuration with filetypes = { 'lua' }, then compare it with Markdown and Rust files. Use the reported coredumpctl info harper-ls stack trace and verify behavior on the Arch Linux package versions mentioned. Done means opening a Lua file no longer causes harper-ls to abort.

Written by the indexing model from the issue text.