coc.nvim fails to start language server with error about "unregistered dependency token ElmWorkspaces"

I’ve used coc.nvim for a while with a variety of languages and I’m trying to get started with Elm. I’ve installed this language server and its dependencies in my local node_modules directory and configured coc.nvim like so:

{
  ...
    "elmLS": {
      "command": "./assets/node_modules/.bin/elm-language-server",
      "filetypes": ["elm"],
      "rootPatterns": ["elm.json"],
      "elmPath": "./assets/node_modules/.bin/elm",
      "elmReviewPath": "./assets/node_modules/.bin/elm-review",
      "elmFormatPath": "./assets/node_modules/.bin/elm-format",
      "elmTestPath": "./assets/node_modules/.bin/elm-test",
    },
   ...
}

Expected Behavior

coc.nvim starts the language server and I can write Elm code using neovim and code completion, syntax checking etc.

Current Behavior

When I start coc.nvim it gives me this message:

Server languageserver.elmLS failed to start: Pm [Error]: Request
initialize failed with message: Attempted to resolve unregistered dependency token: "ElmWorkspaces"
at su (/home/patrick/dotfiles/.config/nvim/plugged/coc.nvim/build/index.js:38:224)
lp (/home/patrick/dotfiles/.config/nvim/plugged/coc.nvim/build/index.js:37:11261)
at
at Immediate. <anonymous> (/home/patrick/dotfiles/.config/nvim/plugged/coc.nvim/build/index.js:37:11111)
at process Immediate (node: internal/timers:464:21) {
code: -32603,
data: undefined

Possible Solution

Not sure I can help here just yet. Was looking through the source of both coc.nvim and elm-language-server and it’s hard to tell where this error is even coming from. I suspect it’s from a dependency of elm-language-server.

Steps to Reproduce

1. Install elm-language-server and its dependencies
2. Configure coc.nvim
3. Edit a Elm file

Your Environment

• Version used: 1.6.0
• Editor used: neovim 0.4.3
• Environment name and version: Node 16.3.0
• Operating System and version: Ubuntu 20.04

[patreeceeo]

That gives me an idea… Yup, it must have been because I hadn’t created an elm.json file yet. Now that that exists in an ancestor directory to the file I’m editing the LS starts up successfully. So, user error, though in the friendly spirit of Elm perhaps the error message should be more helpful?

[razzeee]

That’s an internal thing to the language server, you won’t know that from learning elm