Validates an input hash table to produce another hash table

[Heime <heimeborgia@protonmail.com>]

I am writing that validates an input hash table to produce another 
hash table with the result (replacing the directory path with the 
validation value).

(defun path-validation (input-table)

  (cond

      ((hash-table-p input-table)

      ;; Make hash-table for output
      (let ( (output-table (make-hash-table :test 'equal)) )
        (maphash (lambda (key dirpath)
                   (puthash key (not (file-directory-p dirpath)) output-table))
                 input-table)
        output-table))

      (t
         (mapcar (lambda (entry)
              (let ( (key  (car entry))
                     (dirpath  (cdr entry)) )
                (cons key (not (file-directory-p dirpath)))) )
            input-table)) ))


(defun print-hash-table (hash-table &optional bfrn)
  "Print HASH-TABLE to the buffer BFRN."

  (let* ( (bfname (or bfrn "Hash Table"))
          (dbuffer (get-buffer-create (concat "Project " bfname))) )

    (with-current-buffer dbuffer
      (maphash (lambda (key value)
                 (let* ( (start (point)) )
                   (insert (format "%-8s" key))
                   (insert (format "\n    %s\n" value))))
               hash-table))))


(let ( (input-table (make-hash-table :test 'equal)) )

  (puthash "home-dir" "/home/user" input-table)
  (puthash "docs-dir" "/home/user/Documents" input-table)
  (puthash "fake-dir" "/non/existing/path" input-table)

  (print-hash-table input-table "Input Table")

  (let ( validation-table (path-validation input-table) )
    (print-hash-table validation-table "Output Table")  ; <== Problem Here
    (message "Done"))

  (message "Done"))