It is an error to use the following with a missing member:

 • json_object_get_int_member
 • json_object_get_double_member
 • json_object_get_boolean_member
 • json_object_get_null_member
 • json_object_get_string_member
 • json_object_get_array_member
 • json_object_get_object_member

Doing so will lead to CRITICALs like these:
  Json-CRITICAL **: json_object_get_string_member: assertion
    'node != NULL' failed

Instead one of these should be used to determine the existence of the
member:

 • json_object_get_member
 • json_object_has_member

Or, when available, one can use the corresponding
json_object_get_<type>_member_with_default.

#24