Symbols not ligaturised, silently

### I confirm that...

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- [X] I have read "[How to Debug Issues](https://doomemacs.org/d/how2debug)", and will use it to provide as much information about this issue as possible.

- [X] The issue can be reproduced on the **latest** available commit of Doom.

- [X] The issue can be reproduced on a stable release of Emacs, such as 27, 28, or 29. *(Unstable versions end in .50, .60, or .9x)*

### Expected behavior

I have `(ligatures +extra)` under `:ui`, and `(ocaml +tree-sitter)` under `:lang`. I should see `->` rendered as a single arrow character, and `fun` as a lowercase lambda.

### Current behavior

I see no ligatures. There are no error messages or relevant log output.

Tuareg is running, so the mode has been detected as OCaml.

### Steps to reproduce

Open a file with ligaturisable tokens.

### System Information

https://pastebin.com/Fk26pWLM

Reproduce by opening an OCaml file with `(ligatures +extra)` under `:ui` and `(ocaml +tree-sitter)` under `:lang`, then review the linked system information and the issue’s configuration context. Done means `->` renders as a single arrow and `fun` as a lowercase lambda, with the failure no longer occurring silently.

Written by the indexing model from the issue text.