Error on workspace/configuration request from Julia language server

[non-Jedi]

Since julia-vscode/LanguageServer.jl#374, the Julia language server sends a request that looks like:

server-request (id:-100) Tue Nov  5 15:16:06 2019:
(:method "workspace/configuration" :id -100 :params
         (:items
          [(:scopeUri nil :section "julia.format.indent")
           (:scopeUri nil :section "julia.format.indents")
           (:scopeUri nil :section "julia.format.ops")
           (:scopeUri nil :section "julia.format.tuples")
           (:scopeUri nil :section "julia.format.curly")
           (:scopeUri nil :section "julia.format.calls")
           (:scopeUri nil :section "julia.format.iterOps")
           (:scopeUri nil :section "julia.format.comments")
           (:scopeUri nil :section "julia.format.docs")
           (:scopeUri nil :section "julia.format.lineends")])
         :jsonrpc "2.0")

To which eglot responds with:

client-reply (id:-100) ERROR Tue Nov  5 15:16:06 2019:
(:jsonrpc "2.0" :id -100 :result nil :error
          (:code -32603 :message "Internal error"))

This in turn crashes the Julia language server since it expects the result field to be an array. Reading the specification, I think it's correct to expect that.

On the Julia side, I think sending the scopeUri fields as null is incorrect, and I'm assuming this is what triggers the error on the eglot side.

I think the actionable thing on the eglot side is to always send back a correctly formatted reply even for invalid requests?

Backtrace:

Debugger entered--Lisp error: (wrong-type-argument stringp nil)
  expand-file-name(nil)
  locate-dominating-file(nil dir-locals--all-files)
  dir-locals-find-file("")
  hack-dir-local-variables()
  hack-dir-local-variables-non-file-buffer()
  #f(compiled-function () #<bytecode 0x16e0af1>)()
  eglot--call-with-interface((ConfigurationItem nil (:scopeUri :section)) (:scopeUri nil :section "julia.format.indent") #f(compiled-function () #<bytecode 0x16e0af1>))
  #f(compiled-function (jsonrpc-lambda-elem14) #<bytecode 0x16e0aad>)((:scopeUri nil :section "julia.format.indent"))
  mapcar(#f(compiled-function (jsonrpc-lambda-elem14) #<bytecode 0x16e0aad>) [(:scopeUri nil :section "julia.format.indent") (:scopeUri nil :section "julia.format.indents") (:scopeUri nil :section "julia.format.ops") (:scopeUri nil :section "julia.format.tuples") (:scopeUri nil :section "julia.format.curly") (:scopeUri nil :section "julia.format.calls") (:scopeUri nil :section "julia.format.iterOps") (:scopeUri nil :section "julia.format.comments") (:scopeUri nil :section "julia.format.docs") (:scopeUri nil :section "julia.format.lineends")])
  #f(compiled-function (arg1 arg2 &rest rest) "Handle server request workspace/configuration." #<bytecode 0x167a931>)(#<eglot-lsp-server eglot-lsp-server> workspace/configuration :items [(:scopeUri nil :section "julia.format.indent") (:scopeUri nil :section "julia.format.indents") (:scopeUri nil :section "julia.format.ops") (:scopeUri nil :section "julia.format.tuples") (:scopeUri nil :section "julia.format.curly") (:scopeUri nil :section "julia.format.calls") (:scopeUri nil :section "julia.format.iterOps") (:scopeUri nil :section "julia.format.comments") (:scopeUri nil :section "julia.format.docs") (:scopeUri nil :section "julia.format.lineends")])
  apply(#f(compiled-function (arg1 arg2 &rest rest) "Handle server request workspace/configuration." #<bytecode 0x167a931>) #<eglot-lsp-server eglot-lsp-server> workspace/configuration (:items [(:scopeUri nil :section "julia.format.indent") (:scopeUri nil :section "julia.format.indents") (:scopeUri nil :section "julia.format.ops") (:scopeUri nil :section "julia.format.tuples") (:scopeUri nil :section "julia.format.curly") (:scopeUri nil :section "julia.format.calls") (:scopeUri nil :section "julia.format.iterOps") (:scopeUri nil :section "julia.format.comments") (:scopeUri nil :section "julia.format.docs") (:scopeUri nil :section "julia.format.lineends")]))
  eglot-handle-request(#<eglot-lsp-server eglot-lsp-server> workspace/configuration :items [(:scopeUri nil :section "julia.format.indent") (:scopeUri nil :section "julia.format.indents") (:scopeUri nil :section "julia.format.ops") (:scopeUri nil :section "julia.format.tuples") (:scopeUri nil :section "julia.format.curly") (:scopeUri nil :section "julia.format.calls") (:scopeUri nil :section "julia.format.iterOps") (:scopeUri nil :section "julia.format.comments") (:scopeUri nil :section "julia.format.docs") (:scopeUri nil :section "julia.format.lineends")])
  apply(eglot-handle-request #<eglot-lsp-server eglot-lsp-server> workspace/configuration (:items [(:scopeUri nil :section "julia.format.indent") (:scopeUri nil :section "julia.format.indents") (:scopeUri nil :section "julia.format.ops") (:scopeUri nil :section "julia.format.tuples") (:scopeUri nil :section "julia.format.curly") (:scopeUri nil :section "julia.format.calls") (:scopeUri nil :section "julia.format.iterOps") (:scopeUri nil :section "julia.format.comments") (:scopeUri nil :section "julia.format.docs") (:scopeUri nil :section "julia.format.lineends")]))
  #f(compiled-function (server method params) #<bytecode 0x1697cf1>)(#<eglot-lsp-server eglot-lsp-server> workspace/configuration (:items [(:scopeUri nil :section "julia.format.indent") (:scopeUri nil :section "julia.format.indents") (:scopeUri nil :section "julia.format.ops") (:scopeUri nil :section "julia.format.tuples") (:scopeUri nil :section "julia.format.curly") (:scopeUri nil :section "julia.format.calls") (:scopeUri nil :section "julia.format.iterOps") (:scopeUri nil :section "julia.format.comments") (:scopeUri nil :section "julia.format.docs") (:scopeUri nil :section "julia.format.lineends")]))
  jsonrpc-connection-receive(#<eglot-lsp-server eglot-lsp-server> (:method "workspace/configuration" :id -100 :params (:items [(:scopeUri nil :section "julia.format.indent") (:scopeUri nil :section "julia.format.indents") (:scopeUri nil :section "julia.format.ops") (:scopeUri nil :section "julia.format.tuples") (:scopeUri nil :section "julia.format.curly") (:scopeUri nil :section "julia.format.calls") (:scopeUri nil :section "julia.format.iterOps") (:scopeUri nil :section "julia.format.comments") (:scopeUri nil :section "julia.format.docs") (:scopeUri nil :section "julia.format.lineends")]) :jsonrpc "2.0"))
  jsonrpc--process-filter(#<process EGLOT (tmp/julia-mode)> "Content-Length: 582\015\n\015\n{\"method\":\"workspace/configuration\",\"id\":-100,\"params\":{\"items\":[{\"scopeUri\":null,\"section\":\"julia.format.indent\"},{\"scopeUri\":null,\"section\":\"julia.format.indents\"},{\"scopeUri\":null,\"section\":\"julia.format.ops\"},{\"scopeUri\":null,\"section\":\"julia.format.tuples\"},{\"scopeUri\":null,\"section\":\"julia.format.curly\"},{\"scopeUri\":null,\"section\":\"julia.format.calls\"},{\"scopeUri\":null,\"section\":\"julia.format.iterOps\"},{\"scopeUri\":null,\"section\":\"julia.format.comments\"},{\"scopeUri\":null,\"section\":\"julia.format.docs\"},{\"scopeUri\":null,\"section\":\"julia.format.lineends\"}]},\"jsonrpc\":\"2.0\"}")

[nemethf]

I think the client reply above is not in line with the specification, but because of different reasons. The specification says:

interface ResponseMessage extends Message {
...
/**
 * The result of a request. This member is REQUIRED on success.
 * This member MUST NOT exist if there was an error invoking the method.
 */
result?: string | number | boolean | object | null;

So the result part should be omitted.

But having an "Internal error" is a problem of its own.

[joaotavora]

There are two bugs here.

1. A jsonrpc.el bug.
2. An eglot bug, but maybe somewhere else in Emacs.

The first is my doing, but seems easy to fix. The second I have to understand a bit better.

[joaotavora]

A jsonrpc.el bug.

I've fixed this in jsonrpc.el 1.0.8 which should appear tomorrow on GNU Elpa. This is the path, if your're interested:

commit a8dbb7cc865f227a39708df3fe8d24e6f52b6e28
Author: João Távora <[email protected]>
Date:   Tue Nov 5 23:37:30 2019 +0000

    Follow JSONRPC spec by not sending :result field on errors
    
    Also don't send :error field on non-errors.
    
    * lisp/jsonrpc.el (jsonrpc--reply): Don't send :result and :error
    if none supplied.
    (Version): Bump to 1.0.8

diff --git a/lisp/jsonrpc.el b/lisp/jsonrpc.el
index 41cd84627b..abab445fe5 100644
--- a/lisp/jsonrpc.el
+++ b/lisp/jsonrpc.el
@@ -5,7 +5,7 @@
 ;; Author: João Távora <[email protected]>
 ;; Keywords: processes, languages, extensions
 ;; Package-Requires: ((emacs "25.2"))
-;; Version: 1.0.7
+;; Version: 1.0.8
 
 ;; This is an Elpa :core package.  Don't use functionality that is not
 ;; compatible with Emacs 25.2.
@@ -460,9 +460,13 @@ jsonrpc--json-encode
                                          (json-null nil))
                                      (json-encode object)))))
 
-(cl-defun jsonrpc--reply (connection id &key (result nil result-supplied-p) error)
+(cl-defun jsonrpc--reply
+    (connection id &key (result nil result-supplied-p) (error nil error-supplied-p))
   "Reply to CONNECTION's request ID with RESULT or ERROR."
-  (jsonrpc-connection-send connection :id id :result result :error error))
+  (apply #'jsonrpc-connection-send connection
+         `(:id ,id
+               ,@(and result-supplied-p `(:result ,result))
+               ,@(and error-supplied-p `(:error ,error)))))
 
 (defun jsonrpc--call-deferred (connection)
   "Call CONNECTION's deferred actions, who may again defer themselves."

[joaotavora]

Regarding the second bug, can you try the commit I just pushed?

[non-Jedi]

Using 21f8d40, things seem to work without breaking:

server-request (id:-100) Wed Nov  6 07:55:09 2019:
(:method "workspace/configuration" :id -100 :params
         (:items
          [(:scopeUri nil :section "julia.format.indent")
           (:scopeUri nil :section "julia.format.indents")
           (:scopeUri nil :section "julia.format.ops")
           (:scopeUri nil :section "julia.format.tuples")
           (:scopeUri nil :section "julia.format.curly")
           (:scopeUri nil :section "julia.format.calls")
           (:scopeUri nil :section "julia.format.iterOps")
           (:scopeUri nil :section "julia.format.comments")
           (:scopeUri nil :section "julia.format.docs")
           (:scopeUri nil :section "julia.format.lineends")])
         :jsonrpc "2.0")

client-reply (id:-100) Wed Nov  6 07:55:09 2019:
(:jsonrpc "2.0" :id -100 :result
          [nil nil nil nil nil nil nil nil nil nil])

Thanks for fixing this. I appreciate your work on eglot and elsewhere in emacs.