RPC errors when trying to connect to the LSP server

**Describe the bug**
When starting an F# file, or running an operation that requires the LSP server being queried, I get `RPC[Error]` of varying types:

1. When starting a file, the error is it couldn't find the last non-whitespace char
2. When trying to comment a line using Tim Pope's `vim-commentary` plugin (which I've bound to `gcc`, for example), the error is it can't find a triggering char.
3. For auto-complete dropdown, it's a coin toss: sometimes I get the same results as I get using `Ionide` for VSCode, and sometimes I get very partial results.

**To Reproduce**
As indicated in the description, either open an F# or perform an operation that requires LSP server interaction.

**Expected behaviour**
No RPC errors so the LSP communication is fluid and I get the full benefits of using the plugin.

**Screenshots**



**Environment (please complete the following information):**
- OS: ArchLinux (kept up-to-date on a daily basis, all packages are at the latest available on AUR)
- Vim / Neovim version: NVIM 0.9.1, Release, LuaJIT 2.1.0-beta3
- dotnet SDK version: 7.0.306
- mono / .Net Framework version: N/A (on Linux, using `dotnet`)

**Additional context**
I don't know if it's important, but I've `fsautocomplete` installed *globally*, version 0.61.1 and am starting the plugin in NVIM via the following call:
```
let g:fsharp#fsautocomplete_command = [ "fsautocomplete" ]
let g:fsharp#lsp_codelens = 0
```