Preserve integer precision and object key order in fromjson #19

fromjson can lose precision when decoding large integer tokens. It can also lose object key order when decoding through unordered Go maps.

Both show up when reading JSON configuration:

{% set config = '{"id":9007199254740993}' | fromjson %}
{{ config.id }}
{% for name in '{"upf":1,"amf":2}' | fromjson %}{{ name }};{% endfor %}

Expected rendered values:

9007199254740993
upf;amf;

I’m putting together a PR that retains numeric tokens as json.Number until their type is determined and builds ordered dictionaries from the input. The same handling applies to nested objects and arrays.

The decoder will also check for trailing data after the first complete JSON value and return parsing errors with context.

I’ll link the PR here with regression tests for integer precision and key order. For the Python reference, fromjson is registered using json.loads, since it isn’t a built-in Jinja2 filter. Integer preservation remains limited to the Go engine’s supported range.