No syntax highlighting for Gleam in telescope preview

[zbyju]

Description

Although my syntax highlighting works when writing gleam (through treesitter), it doesn't work in telescope's preview.

I'm using lunarvim with some small tweaks (but I don't think they should break this)

Here is a small gleam code if you wanna quickly test it:

import gleam/io

pub fn main() {
  io.println("hello, friend!")
}

Neovim version

NVIM v0.10.2
Build type: Release
LuaJIT 2.1.1731485912

Operating system and version

macOS 15.1.1 (24B2091)

Telescope version / branch / rev

    version 0.1.6         tag     0.1.6         branch  0.1.x         commit  6312868

checkhealth telescope

==============================================================================
telescope: require("telescope.health").check()

Checking for required plugins ~
- OK plenary installed.
- OK nvim-treesitter installed.

Checking external dependencies ~
- OK rg: found ripgrep 14.1.1
- OK fd: found fd 10.2.0

===== Installed extensions ===== ~

Telescope Extension: `fzf` ~
- OK lib working as expected
- OK file_sorter correctly configured
- OK generic_sorter correctly configured

Telescope Extension: `projects` ~
- No healthcheck provided

Steps to reproduce

(0. Install lunarvim)

1. Install telescope
2. Look for old files (or anything where you have access to preview the file)
3. Look for a gleam file

Expected behavior

No response

Actual behavior

I don't get any syntax highlighting for gleam files

Minimal config

lunarvim

[miEsMar]

I think this issue is closely related.
I think the root cause is that built-in Telescope previewer does not apply the same filetype rules as it is normally done for normal buffers.
I don't know (I just asked on the last ocmment in the linked issue) if there is a way to set ft for telescope previewer based on file extension etc., maybe through an autocmd.
I hope this gets solved one day.