Sets a scalar value inside the given node.
The contents of the given `GValue` are copied into the `JsonNode`.
The following `GValue` types have a direct mapping to JSON types:
JSON-GLib will also automatically promote the following `GValue` types:
It is an error to call this on an immutable node, or on a node which is not a value node.
this |
a node initialized to `JSON_NODE_VALUE` |
value |
the value to set |