bug#67480: 30.0.50; Cannot start eglot

[Stefan Monnier]

>  1. `emacs -Q`
>  2. Open a src file and `M-x eglot`
>  3. Get the following message:
[...]
>  Loading external-completion (native compiled elisp)...done
>  Unbound slot: eglot-lsp-server, "#<eglot-lsp-server
>  eglot-lsp-server-1feea1d8dd60>", -events-buffer, oref
>  error in process filter: Unbound slot: eglot-lsp-server,
>  "#<eglot-lsp-server eglot-lsp-server-1feea1d8dd60>", -events-buffer, oref
>  [2 times]
>  ```
[...]
> After I tried to build different version, I can confirm the problem
> occurs after this commit:
> https://git.savannah.gnu.org/cgit/emacs.git/commit/?id=6c47931a1ad4de4af3f147b9604169c2441100fe

Thanks, that was very helpful.  This commit makes it so `:accessor`
functions behave like `:reader` functions, i.e. behave like
`slot-value`, whereas the old code returned nil if the slot was
"unbound".

Maybe the better fix is something like the patch below?
João?


        Stefan


diff --git a/lisp/jsonrpc.el b/lisp/jsonrpc.el
index 52ffb220d8b..4298d75c5bf 100644
--- a/lisp/jsonrpc.el
+++ b/lisp/jsonrpc.el
@@ -71,6 +71,7 @@ jsonrpc-connection
     :accessor jsonrpc--request-continuations
     :documentation "A hash table of request ID to continuation lambdas.")
    (-events-buffer
+    :initform nil
     :accessor jsonrpc--events-buffer
     :documentation "A buffer pretty-printing the JSONRPC events")
    (-events-buffer-scrollback-size