30.0.50; 'New' error message when using eglot

[Pedro Andres Aranda Gutierrez <paaguti@gmail.com>]

Steps to reproduce:

Install pylsp 1.7.1

emacs -Q -l micro-eglot.el <any python file>

----------- micro-eglot.el -----------------------
(require 'package)
(add-to-list 'package-archives
             '("melpa" . "https://melpa.org/packages/") t)

(eval-when-compile
  (require 'use-package))
(require 'bind-key)

(setq use-package-always-ensure t)
(unless (file-directory-p package-user-dir)
    (package-refresh-contents))

(use-package jsonrpc
  :ensure nil)

(defun my/eglot-mode-hook ()
  (interactive)
  (message "Adding yasnippets to eglot for %s" major-mode))

(use-package eglot
  :ensure nil
  :defines eglot-server-programs
  :hook ((eglot-managed-mode . my/eglot-mode-hook)
         (python-mode . eglot-ensure))
  :config
  (message "Configuring eglot")
  (setq eglot-server-programs '(;;(python-mode  . ("jedi-language-server"))
                                (python-mode . ("pylsp")))))
----------------------------------------------

You should see:

error in process filter: Wrong type argument: plistp, [] [2 times]

Repeatedly, once the LSP is running

In GNU Emacs 30.0.50 (build 1, x86_64-apple-darwin17.7.0, NS
 appkit-1561.61 Version 10.13.6 (Build 17G14042)) of 2023-02-23 built on
 paag.local
Repository revision: fad3665069740e002fcb7f9313f9eeec81ad9a0c
Repository branch: master
Windowing system distributor 'Apple', version 10.3.1561
System Description:  Mac OS X 10.13.6

Configured using:
 'configure PKG_CONFIG_PATH=/usr/local/lib/pkgconfig
 LDFLAGS=-L/usr/local/lib CPPFLAGS=-I/usr/local/include CC=clang
 OBJC=clang 'CFLAGS=-g -O3''

Configured features:
ACL GMP GNUTLS JPEG JSON LIBXML2 MODULES NOTIFY KQUEUE NS PDUMPER PNG
SQLITE3 THREADS TIFF TOOLKIT_SCROLL_BARS WEBP XIM ZLIB

Important settings:
  value of $LC_COLLATE: es_ES.UTF-8
  value of $LC_CTYPE: es_ES.UTF-8
  value of $LC_MESSAGES: es_ES.UTF-8
  value of $LC_MONETARY: es_ES.UTF-8
  value of $LC_NUMERIC: es_ES.UTF-8
  value of $LC_TIME: es_ES.UTF-8
  value of $LANG: es_ES.UTF-8
  locale-coding-system: utf-8-unix

Major mode: Python

Minor modes in effect:
  eglot--managed-mode: t
  flymake-mode: t
  override-global-mode: t
  tooltip-mode: t
  global-eldoc-mode: t
  eldoc-mode: t
  show-paren-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  tool-bar-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  line-number-mode: t
  transient-mark-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message yank-media puny dired
dired-loaddefs rfc822 mml mml-sec epa derived epg rfc6068 epg-config
gnus-util mm-decode mm-bodies mm-encode mail-parse rfc2231 mailabbrev
gmm-utils mailheader sendmail rfc2047 rfc2045 ietf-drums mm-util
mail-prsvr mail-utils time-date eglot external-completion array
filenotify xref flymake-proc flymake thingatpt compile
text-property-search imenu python rx project treesit comint ansi-osc
ring ansi-color jsonrpc ert pp ewoc debug backtrace find-func pcase
warnings icons cl-extra help-mode use-package use-package-ensure
use-package-delight use-package-diminish use-package-bind-key bind-key
easy-mmode use-package-core package browse-url url url-proxy url-privacy
url-expand url-methods url-history url-cookie generate-lisp-file
url-domsuf url-util mailcap url-handlers url-parse auth-source cl-seq
eieio eieio-core cl-macs password-cache json subr-x map byte-opt gv
bytecomp byte-compile url-vars cl-loaddefs cl-lib rmc iso-transl tooltip
cconv eldoc paren electric uniquify ediff-hook vc-hooks lisp-float-type
elisp-mode mwheel term/ns-win ns-win ucs-normalize mule-util
term/common-win tool-bar dnd fontset image regexp-opt fringe
tabulated-list replace newcomment text-mode lisp-mode prog-mode register
page tab-bar menu-bar rfn-eshadow isearch easymenu timer select
scroll-bar mouse jit-lock font-lock syntax font-core term/tty-colors
frame minibuffer nadvice seq simple cl-generic indonesian philippine
cham georgian utf-8-lang misc-lang vietnamese tibetan thai tai-viet lao
korean japanese eucjp-ms cp51932 hebrew greek romanian slovak czech
european ethiopic indian cyrillic chinese composite emoji-zwj charscript
charprop case-table epa-hook jka-cmpr-hook help abbrev obarray oclosure
cl-preloaded button loaddefs theme-loaddefs faces cus-face macroexp
files window text-properties overlay sha1 md5 base64 format env
code-pages mule custom widget keymap hashtable-print-readable backquote
threads kqueue cocoa ns multi-tty make-network-process emacs)

Memory information:
((conses 16 99707 11890)
 (symbols 48 11573 0)
 (strings 32 33723 2299)
 (string-bytes 1 1028835)
 (vectors 16 23053)
 (vector-slots 8 316794 15593)
 (floats 8 68 15)
 (intervals 56 559 0)
 (buffers 976 14))

-- 
Fragen sind nicht da um beantwortet zu werden,
Fragen sind da um gestellt zu werden
Georg Kreisler

Headaches with a Juju log:
unit-basic-16: 09:17:36 WARNING juju.worker.uniter.operation we should
run a leader-deposed hook here, but we can't yet