Codeium crashes on vim.fn.json_encode() when triggered in non-UTF-8 buffers (e.g., minified files or preview panels)

[agity7]

Summary

Codeium sometimes crashes with Vim:E474: String ... contains byte that does not start any UTF-8 character when trying to generate completions on buffers containing non-UTF-8 or binary-like content.

How to Reproduce

1. Open a .min.js, .mjs, or .pem file, or any non-UTF-8 content
2. Start typing to trigger completions
3. Neovim crashes with this error:

[C]: in function 'json_encode'
.../codeium.nvim/lua/codeium/io.lua:410: in function 'post'
...

Cause

vim.fn.json_encode() is being called on raw buffer content without verifying if the buffer:

• Is valid UTF-8
• Is of a proper filetype (nofile, prompt, etc.)
• Should be excluded (Telescope, Spectre, etc.)

Suggested Fix

1. Wrap vim.fn.json_encode(payload) in pcall() to avoid crashing:

   local ok, encoded = pcall(vim.fn.json_encode, payload)
   if not ok then return end
   

2. Don’t trigger completions in buffers with:

buftype ~= ""
filetype == "TelescopePrompt"
buffer filename under .codeium/

Why This Matters

This bug silently crashes Codeium in common dev workflows. Users editing modern JS/TS stacks or using preview UIs (Telescope, Spectre) hit this often.

Thanks!