`flymake-eslint-enable` works when enabled from minibuffer but fails when started from major mode hook

[ovistoica]

Here's my config

(use-package flymake
  :ensure flymake
  :demand
  :hook (prog-mode . flymake-mode)
  :defines
  flymake-mode
  :bind
  ("M-n"     . flymake-goto-next-error)
  ("M-p"     . flymake-goto-prev-error)
  ("<f12>"   . flymake-goto-next-error)
  ("C-<f12>" . flymake-goto-next-error)
  ("C-c !"   . flymake-show-buffer-diagnostics))

(use-package flymake-eslint
  :ensure flymake-eslint
  :after (flymake)
  :hook
  (js2-mode . flymake-eslint-enable)
  (web-mode . flymake-eslint-enable)
  (typescript-ts-mode .  (lambda () (flymake-eslint-enable)))
  (tsx-ts-mode . (lambda () (flymake-eslint-enable))))

If I open a ts or tsx file and then I do M-x flymake-eslint-enable it works
But as a hook trigger from the above config it fails

Note: It's now written with lambda as I hoped that would solve it but I get the same error if have hooks configured like

(mode . flymake-eslint-enable)

I'm using treesitter & eglot

Messages Log

error in process sentinel: flymake--handle-report: Can’t find state for flymake-proc-legacy-flymake in ‘flymake--state’
error in process sentinel: Can’t find state for flymake-proc-legacy-flymake in ‘flymake--state’
error in process sentinel: flymake--handle-report: Can’t find state for flymake-eslint--checker in ‘flymake--state’
error in process sentinel: Can’t find state for flymake-eslint--checker in ‘flymake--state’

[ovistoica]

Update: Figured it out. The issue was that eglot was taking over flymake, removing any other backends that were set. In the eglot documentation, it's suggested to add flymake to eglot-stay-out-of but that stops eglot from showing errors through flymake which is not what you'd want

Ended on with this as a working solution:

(defun os/enable-eslint-if-typescript ()
 "Enable eslint if typescript mode"
 (when (or (eq major-mode 'tsx-ts-mode)
           (eq major-mode 'typescript-ts-mode))
   (flymake-eslint-enable)))

(add-hook 'eglot-managed-mode-hook #'os/enable-eslint-if-typescript)