Make receiver consistent across all methods of ServiceError (#3468)

* Make receiver consistent across all methods of ServiceError

* Use `head_ref` for PRs

and `ref` for pushes. `head_ref` refers to the reference of the base branch of the pull request. For non-pull request events, github.head_ref will not be set.

.github/workflows/report-coverage.yml

@@ -16,7 +16,7 @@ jobs:
         uses: actions/checkout@v4
         with:
           repository: ${{ github.event.workflow_run.head_repository.full_name }}
-          ref: ${{ github.event_name == 'pull_request' && github.ref || github.head_ref }}
+          ref: ${{ github.event_name == 'pull_request' && github.head_ref || github.ref }}
 
       - name: Download test coverage
         uses: dawidd6/action-download-artifact@v3

pkg/error.go

@@ -29,7 +29,7 @@ type (
 		Fault bool
 		// History tracks all the individual errors that were built into this error, should
 		// this error have been merged.
-		history []ServiceError
+		history []*ServiceError
 		// err holds the original error if exists.
 		err error
 	}
@@ -238,12 +238,12 @@ func MergeErrors(err, other error) error {
 }
 
 // History returns the history of error revisions, ignoring the result of any merges.
-func (e ServiceError) History() []ServiceError {
+func (e *ServiceError) History() []*ServiceError {
 	if len(e.history) > 0 {
 		return e.history
 	}
 
-	return []ServiceError{e}
+	return []*ServiceError{e}
 }
 
 // Error returns the error message.