fix(core): interpolate {{value}} with the key for field: "@key"

[slegarraga]

Summary

With field: "@key", the {{value}} message placeholder interpolated to Object{} instead of the property key. Fixes #2922.

Root cause

getLintTargets correctly passes the property key as the target value for @key (so the function itself runs against the key). But when building the message variables, processTargetResults recomputed the value from the resolved path:

const value = path.length === 0 ? document.data : get(document.data, path);

For a @key target the path points at the keyed entry (['responses', '404']), so get(document.data, path) returns the value stored there (an object), and {{value}} rendered as Object{}.

Fix

Pass then.field through to processTargetResults and, for @key targets, use the key (the last path segment) as the message value, consistent with the value the function already received.

Test

Added a test in linter.test.ts. Observed output after the fix:

code: 'rule1'
message: '"404" must be equal to one of the allowed values: "200", "400"'
path: ['responses', '404']
severity: Warning

yarn jest packages/core/src/__tests__/linter.test.ts → 49 passed.

Note: this fixes the {{value}} interpolation. The reported result range still points at the keyed value rather than the key node; that is a separate concern and can be a follow-up if desired.