Rest integration: Can't return entire content of value_json

Hi, my RESTFul integration calls an API that returns a JSON array. I want to save this data as a sensor so I can later use it in templating.

When I try the below code, the sensor state becomes ‘unknown’, but if I change it to 'value_json[0]' it will return the first element of the array just fine. What’s the problem and how do I return the entire array?

This does not work:

rest:
  - resource: https://jsonplaceholder.typicode.com/todos
    scan_interval: 60
    sensor:
      - name: "entirearray"
        value_template: "{{ value_json }}"

But this does:

rest:
  - resource: https://jsonplaceholder.typicode.com/todos
    scan_interval: 60
    sensor:
      - name: "entirearray"
        value_template: "{{ value_json[0] }}"