entity variable is undefined name JS template despite card having valid entity configured

[CalamarBicefalo]

Checklist

• [x] I updated the card to the latest version available
• [x] I cleared the cache of my browser

Describe the bug The entity object is undefined in a javascript template in the name attribute even though:

• The entity attribute is defined
• The entity attribute value is correct and exists. In fact, if I remove the name template, it renders the friendly name of the target attribute

Version of the card Version: 4.1.1

To Reproduce This is the configuration I used:

type: "custom:button-card"
template: card_title
entity: "[[[ return 'input_select.'+variables.room_key+'_activity' ]]]"
name: [[[ return entity.state ]]]

[CalamarBicefalo]

That was in the custom_fields section of a template definition.

Adding the entity to the parent card solved the problem