Create class not working

[Sasanidas]

I have some problems with the phpactor-create-new-class seems the json serialization is not working correclty (it may be related to this issue.
I'm using Emacs 27.1 compiled from the official tarball from the Emacs page.
This is part of the command output

Debugger entered--Lisp error: (wrong-type-argument json-value-p :null) json-serialize((:action "class_new" :parameters (:new_path :null :variant :null :overwrite_existing :null :current_path "/usr/Data_2/Programming/drupal-9.0.6/core/modules/aggregator/src/Entity/Feed.php")) :null-object nil :false-object :json-false)

(let ((json (phpactor--serialize-json (list :action action :parameters arguments))) (output (get-buffer-create "*Phpactor Output*")) (coding-system-for-write 'utf-8) (cwd (phpactor-get-working-dir))) (save-current-buffer (set-buffer output) (erase-buffer)) (save-current-buffer (set-buffer (get-buffer-create "*Phpactor Input*")) (setq default-directory cwd) (erase-buffer) (insert json) (call-process-region (point-min) (point-max) phpactor-executable nil output nil "rpc" (format "--working-dir=%s" default-directory)) (phpactor--parse-json output))) phpactor--rpc("class_new" (:new_path :null :variant :null :overwrite_existing :null :current_path "/usr/Data_2/Programming/drupal-9.0.6/core/modules/aggregator/src/Entity/Feed.php")) (apply #'phpactor-action-dispatch (phpactor--rpc (plist-get callback :action) parameters))

Thank you