Error: Request textDocument/signatureHelp failed.

How are you using the lua-language-server?

Visual Studio Code Extension (sumneko.lua)

Which OS are you using?

Windows

What is the issue affecting?

Completion

Expected Behaviour

VSCode shows function arguments normally.

Actual Behaviour

"Request textDocument/signatureHelp failed" is shown.

[Error - 4:54:31 PM] Request textDocument/signatureHelp failed.
  Message: [16:54:31.780][error][#0:script\core\signature.lua:56]: script\core\signature.lua:56: attempt to index a nil value (local 'argLabel')
stack traceback:
	script\core\signature.lua:56: in upvalue 'makeOneSignature'
	script\core\signature.lua:175: in upvalue 'makeSignatures'
	script\core\signature.lua:209: in function 'core.signature'
	script\provider\provider.lua:783: in function <script\provider\provider.lua:770>
	[C]: in function 'xpcall'
	script\proto\proto.lua:202: in function <script\proto\proto.lua:177>

  Code: -32603 

Reproduction steps

Test code:

---@class ColorClass
local Color = {}

---@alias Color ColorClass|number[]
---@alias AlignMode
---| "center"
---| "left"
---| "right"
---| "justify"

---@param args string|{text:string,wrap:boolean?,font:{path:string,size:integer}?,scale:number?,align:AlignMode?,color:Color?,outline:number?,outlineColor:Color?}
local function fooz(args)
end

The args has to be quite long to trigger it and perhaps with that specific setup of Color and AlignMode too.

Afterwards, simply write fooz( on the next line and the error should appear.

Additional Notes

No response

Log File

file_d%3A_Data_Development_love-11.3-win64_luals-report.log

Reproduisez l’échec avec l’extrait Lua en saisissant fooz( et en demandant l’aide à la signature. Commencez à script/core/signature.lua:56, puis suivez les frames d’appel de makeSignatures et du provider affichées dans la trace. C’est terminé lorsque la requête ne génère plus d’erreur et que VS Code affiche les arguments de la fonction pour cette déclaration.