bug#57725: 29.0.50; eglot: Error when using :initializationOptions

[Augusto Stoffel]

If I attempt to pass :initializationOptions to a server like so:

    (setf (alist-get 'python-mode eglot-server-programs)
          '("jedi-language-server" :initializationOptions eglot--{}))

I get an error:

    Debugger entered--Lisp error: (invalid-slot-name "#<eglot-lsp-server 
eglot-lsp-server-92f0c8>" :initializationOptions)

A workaround is to add this to the eglot-lsp-server defclass:

@@ -788,6 +788,7 @@ treated as in `eglot-dbind'."
    (managed-buffers
     :documentation "List of buffers managed by server."
     :accessor eglot--managed-buffers)
+   (_ :initarg :initializationOptions)
    (saved-initargs
     :documentation "Saved initargs for reconnection purposes."
     :accessor eglot--saved-initargs)

I can also confirm that after the workaround, the options are passed
correctly to the server upon initialization.