fix: resolve failing issues with checkDSL validation on the new grammar

[adriantam]

Description

Correct DSL checker and update test snapshot to correct expected result. In addition, add test to ensure dsl checker able to detect the right error line with empty line in DSL.

References

Close #55

Review Checklist

• I have clicked on "allow edits by maintainers".
• I have added documentation for new/changed functionality in this PR or in a PR to openfga.dev [Provide a link to any relevant PRs in the references section above]
• The correct base branch is being used, if not main
• I have added tests to validate that the change in functionality is working as expected

[miparnisari]

With this auth model, which has a bug:

type group
  relations
    define member as self
    define admin as self

    define can_add as can_manage_group  
    define can_edit as can_manage_group
    define can_delete as can_manage_group
    define can_read as can_manage
    
    define can_manage_group as admin
    define can_manage_users as admin
    define can_view_group as admin or member
    define can_view_users as admin or member

If I start typing another define at the end, I see this:

[adriantam]

With this auth model, which has a bug:

type group
  relations
    define member as self
    define admin as self

    define can_add as can_manage_group  
    define can_edit as can_manage_group
    define can_delete as can_manage_group
    define can_read as can_manage
    
    define can_manage_group as admin
    define can_manage_users as admin
    define can_view_group as admin or member
    define can_view_users as admin or member

If I start typing another define at the end, I see this:

Issue is fixed. Thanks!