List containing null values

[YaYaB]

Currently if a json array contains a value equal to null, the following error will be displayed

    my_elems = '[' + ','.join(my_elems) + ']'
TypeError: sequence item 0: expected str instance, NoneType found                                                              

The following json generates this error:

{
  "test":[null, null, null, {"src": "test"}
}