Error location is unclear if schema is nested and required field isn't set

[suzuki-shunsuke]

Thank you for your great project!

This is a feedback about the error message.
It would be great if we can see where the error occurs easily.

schema.k

schema github_issue_label:
    attrs: github_issue_label_attrs

schema github_issue_label_attrs:
    repository: str
    name: str

foo.k

import .schema

bar = schema.github_issue_label_attrs {
    name: "Urgent"
}

$ kcl foo.k 
Error: EvaluationError
 --> /Users/shunsukesuzuki/Documents/test/kcl/terraform/null/foo.k:3:1
  |
3 | bar = schema.github_issue_label_attrs {
  |  attribute 'repository' of github_issue_label_attrs is required and can't be None or Undefined
  |

The error message shows the location where the error occurs in the caller side (foo.k).

On the other hand, the following error message doesn't show the location where the error occurs in the caller side (bar.k).

bar.k

import .schema

bar = schema.github_issue_label {
    attrs: {
        name: "Urgent"
    }
}

$ kcl bar.k
Error: EvaluationError
 --> /Users/shunsukesuzuki/Documents/test/kcl/terraform/null/schema.k:2:1
  |
2 |     attrs: github_issue_label_attrs
  |  attribute 'repository' of github_issue_label_attrs is required and can't be None or Undefined
  |

I found if I fix bar.k a bit, the error message shows the location.

bar.k

import .schema

bar = schema.github_issue_label {
    attrs: schema.github_issue_label_attrs { # Add type `schema.github_issue_label_attrs`
        name: "Urgent"
    }
}

$ kcl bar.k
Error: EvaluationError
 --> /Users/shunsukesuzuki/Documents/test/kcl/terraform/null/bar.k:4:1
  |
4 |     attrs: schema.github_issue_label_attrs {
  |  attribute 'repository' of github_issue_label_attrs is required and can't be None or Undefined
  |