Unexplained error

[Khelda]

Hello there,

From what I understand from reading the documentation, with an already setup kitty and using VimPlug (I understood that lazy might not be mandatory for this plugin and the config existed before me knowing about lazy), this should not happen :

For information, the setup looks like this :

--
-- Graph plugin configuration file.
--

require 'nix'
local nix = Nix:new()

-- pathing fix
vim.env['PATH'] = vim.env['PATH'] .. ':' .. nix:path("mermaid-cli", "/bin")

-- Plugin setup
require 'diagram'.setup {
    integrations = {
        require 'diagram.integrations.markdown'
    },
    renderer_options = {
        mermaid = { theme = "dark", background = "transparent" },
        plantuml = { charset = "utf-8" },
        d2 = { theme_id = 1, dark_theme_id = 1 },
        gnuplot = { theme = "dark", size = "400,200" }
    }
}

Don't mind the nix bit, it's just for pathing purposes and making sure mmdc is available on path.

[sghng]

I went into the same issue on macOS running latest Neovim. Here's my config

return
{
		-- mermaid rendering
		"3rd/diagram.nvim",
		dependencies = "3rd/image.nvim",
		ft = "markdown",
		config = function()
			require("diagram").setup({
				integrations = { require("diagram.integrations.markdown") },
			})
		end,
	}

I'm also using render-markdown.nvim, this might be related.

[aronvandepol]

I am getting the same error.

[aronvandepol]

I am getting the same error.

It seems to have been an issue with PUPPETEER_EXECUTABLE_PATH

I had not had this set to the right chrome headless shell. Updating this fixed my issue.

[3rd]

@Khelda can you check if you have the same issue @aronvandepol had?

[willgraham345]

I'm running into a similar issue. What exactly do you mean @aronvandepol with the PUPPETEER_EXECUTABLE_PATH? Is that an npm library I should also install?
(forgive the question if it is ignorant, I'm definitely a beginner to Neovim!)

[aronvandepol]

As far as I now understand (do correct me if I’m wrong), Mermaid needs a headless browser environment to render diagrams, which is handled by Puppeteer. diagram.nvim likely uses Puppeteer under the hood to interact with Mermaid and generate the actual image files. Without setting the PUPPETEER_EXECUTABLE_PATH environment variable, Puppeteer either can't find a browser or fails to launch one — so the diagrams just don’t render. Setting that path like this:

PUPPETEER_EXECUTABLE_PATH="/Users/aron/.cache/puppeteer/chrome-headless-shell/mac_arm-134.0.6998.35/chrome-headless-shell-mac-arm64/chrome-headless-shell"

solved it for me.

[Khelda]

Sorry for the delay, needed to get shit done. So, if I understood, ensuring puppeteer is on PATH should clear the problem ? Or did I misunderstood ?

[Khelda]

And @3rd I only ever got a mmdc failed to render diagram and that's it, nothing in logs...

[jorgibob]

I believe the issue is lies here:

diagram.nvim/lua/diagram/renderers/mermaid.lua

Lines 66 to 70 in 84fe677

	on_stderr = function(job_id, data, event)
	local error_msg = table.concat(data, "\n")
	vim.notify("diagram/mermaid: mmdc failed to render diagram. Error: " .. error_msg, vim.log.levels.ERROR)
	return nil
	end,

The vim.notify call is not guarded by a check to see if the stderr stream contains any data. I'm not very familiar with lua, but the following seems to fix it:

if #error_msg > 0 then
  vim.notify(...)
end

[bedlamzd]

FYI added notify call to on_exit callback, to see what exit code was returned by d2

D2 Jobstart call

  local job_id = vim.fn.jobstart(
    command,
    {
      on_stdout = function(job_id, data, event) end,
      on_stderr = function(job_id, data, event)
        local error_msg = table.concat(data, "\n")
        vim.notify("diagram/d2: d2 failed to render diagram" .. error_msg, vim.log.levels.ERROR)
        return nil
      end,
      on_exit = function(job_id, exit_code, event)
        local msg = string.format("Job %d exited with code %d.", job_id, exit_code)
        vim.notify(msg)
        -- vim.api.nvim_out_write(msg .. "\n")
      end,
    }
  )

And when rendering got these messages

diagram/d2: d2 failed to render diagramsuccess: successfully compiled nvim.bedlamzd/6zRA6X/4 to ~/.cache/nvim-test/diagram-cache/d2/26e97b59f6863a26129986cb8cea56906bd7981ba0baae9065a8dce0559131ef.png in 181.435717ms                                                                                                                                                                                                                  
diagram/d2: d2 failed to render diagram                                                                                                                                                                              
Job 8 exited with code 0.                                                                                                                                                                                            
Error executing vim.schedule lua callback: Vim:diagram/d2: d2 failed to render diagram                                                                                                                               
stack traceback:                                                                                                                                                                                                     
        [C]: in function 'jobwait'                                                                                                                                                                                   
        ...l/share/nvim-test/lazy/diagram.nvim/lua/diagram/init.lua:90: in function ''                                                                                                                               
        vim/_editor.lua: in function <vim/_editor.lua:0>   

So in reality there's no error. The same happens with other renderers and I think that makes sense. I assume they write the diagram itself to stdout, so it can be piped to a file, while all logging goes to stderr.

For clarity - diagrams do render for me (although if the diagram is on the first line, the image doesn't appear, which made the error above appear like a genuine error, but that's a different issue)

And just in case - I have markview installed, but the error happens regardless if it's enabled or not

Not sure if it's possible to inspect exit code inside the callback (looking at the docs, doesn't seem so), so I think the best thing to do here is something like this:

  local error_msg = ""
  local job_id = vim.fn.jobstart(command, {
    on_stdout = function(job_id, data, event) end,
    on_stderr = function(job_id, data, event)
      error_msg = table.concat(data, "\n")
    end,
    on_exit = function(job_id, exit_code, event)
      if exit_code ~= 0 then
        local msg = string.format("Job %d exited with code %d. Error: %s", job_id, exit_code, error_msg)
        vim.notify(msg)
      end
      -- vim.api.nvim_out_write(msg .. "\n")
    end,
  })

Unfortunately what I wrote doesn't work. I don't know much about lua or neovim api there. Looks like callbacks executed in isolation somehow and for on_exit there is no change in error_msg variable, even though it's called after on_stderr. So I leave this idea to more competent people :)

[sghng]

I re-enabled this plugin, somehow the error is gone -- but the rendering is still incorrect. The diagram is too small, and it persists between tmux panes.

[tkolleh]

Yeah, I can't get this to work on OS: macOS 15.6.1 24G90 arm64 with NVIM v0.12.0-dev-949+g5f9f706462, having followed the installation instructions and tried different approaches to set PUPPETEER_EXECUTABLE_PATH.