JSON_ELEMENT_TYPE_NULL should be 0

[KoboldSoftware]

When passing an unitialized (or zero'ed) json_element_t to json_free()

typed(json_element) root_element = { 0 };
... do something, maybe fail along the way ...
json_free(&root_element);

it assumes JSON_ELEMENT_TYPE_STRING and calls free(root_element.value.as_string).
While calling free(NULL) is valid and does nothing, it would be more intuitive to change the enum

from
typedef enum json_element_type_e {
JSON_ELEMENT_TYPE_STRING = 0,
JSON_ELEMENT_TYPE_NUMBER,
JSON_ELEMENT_TYPE_OBJECT,
JSON_ELEMENT_TYPE_ARRAY,
JSON_ELEMENT_TYPE_BOOLEAN,
JSON_ELEMENT_TYPE_NULL
} typed(json_element_type);

to
typedef enum json_element_type_e {
JSON_ELEMENT_TYPE_NULL = 0,
JSON_ELEMENT_TYPE_STRING,
JSON_ELEMENT_TYPE_NUMBER,
JSON_ELEMENT_TYPE_OBJECT,
JSON_ELEMENT_TYPE_ARRAY,
JSON_ELEMENT_TYPE_BOOLEAN
} typed(json_element_type);

as to avoid further confusion and a potential crash if the value happens to be non-NULL.
That way json_free() will not call free() on the invalid element.

The initialization
typed(json_element) root_element = { 0 };
may only set the type to 0 but leave the value uninitialized, depending on the C standard. With C99 the whole struct is memset to 0.

[whyisitworking]

This does look intuitive. You can open an MR.