Improved error message when trying to use `in` for set membership

[cdisselkoen]

Category

Other

Describe the feature you'd like to request

As pointed out by @khieta in this comment on RFC 18. For errors like

context.solution_id in principal.solution_ids

instead of the not-very-helpful error message

Errors: while evaluating policy policy0, encountered the following error: type error: expected (entity of type any_entity_type), got string

we should have something more helpful like this

type error: in expects an entity on the LHS. Use .contains() for set membership

Describe the solution you'd like

As above.

Describe alternatives you've considered

RFC 18 discusses alternatives, but this is something we can do now to help while RFC 18 continues to be discussed and/or implemented.

Additional context

No response

Is this something that you'd be interested in working on?

• 👋 I may be able to implement this feature request
• ⚠️ This feature might incur a breaking change