Cannot access a list item with an expression

[barmac]

Describe the Bug

If I put an expression in the brackets, I get null results instead of the value, even though the expression evaluates to a number.

Steps to Reproduce

https://nikku.github.io/feel-playground/?e=for+i+in+2..count%28l%29+return+l%5Bi%5D+%2B+l%5Bi-1%5D&c=%7B%0A++%22l%22%3A+%5B2%2C3%2C5%2C8%2C13%5D%0A%7D&t=expression&st=true

There is a workaround: https://nikku.github.io/feel-playground/?e=for+i+in+2..count%28l%29+return+l%5Bi%5D+%2B+l%5B%7Br%3A+i-1%7D.r%5D&c=%7B%0A++%22l%22%3A+%5B2%2C3%2C5%2C8%2C13%5D%0A%7D&t=expression&st=true

Expected Behavior

Element of the given index is accessed.

Environment

• Host (Browser/Node version), if applicable: [e.g. MS Edge 18, Chrome 69, Node 10 LTS]
• OS: [e.g. Windows 7]
• Library version: [e.g. 2.0.0]

Context

Related to https://jira.camunda.com/browse/SUPPORT-29896

[barmac]

What is probably happening is that we interpret the expression as a filter.

[nikku]

This is a bug. Thanks for the good report!