JSON readtable error

[guibor]

I get the following error:

"json-read: JSON readtable error:"

whenever I run code-cells-convert-ipynb()

backtrace

Debugger entered--Lisp error: (json-readtable-error 35)
  signal(json-readtable-error (35))
  json-read()
  code-cells--guess-mode()
  code-cells-convert-ipynb()