Cloudwatch: Unwrap errors - throw error from upstream (#36334) (#37993)

* Unwrap errors - throw error from upstream

* Fixes according to reviewer's comments

* Fix linting

* Remove unused code

(cherry picked from commit 050dc7bc8f)

Co-authored-by: Dimitris Sotirakis <dimitrios.sotirakis@grafana.com>

pkg/api/metrics.go

@@ -6,14 +6,13 @@ import (
 	"net/http"
 
 	"github.com/grafana/grafana-plugin-sdk-go/backend"
-	"github.com/grafana/grafana/pkg/expr"
-	"github.com/grafana/grafana/pkg/models"
-	"github.com/grafana/grafana/pkg/plugins"
-
 	"github.com/grafana/grafana/pkg/api/dtos"
 	"github.com/grafana/grafana/pkg/api/response"
 	"github.com/grafana/grafana/pkg/bus"
 	"github.com/grafana/grafana/pkg/components/simplejson"
+	"github.com/grafana/grafana/pkg/expr"
+	"github.com/grafana/grafana/pkg/models"
+	"github.com/grafana/grafana/pkg/plugins"
 	"github.com/grafana/grafana/pkg/util"
 )
 

pkg/tsdb/cloudwatch/time_series_query.go

@@ -98,6 +98,12 @@ func (e *cloudWatchExecutor) executeTimeSeriesQuery(ctx context.Context, req *ba
 	}
 
 	if err := eg.Wait(); err != nil {
+		dataResponse := backend.DataResponse{
+			Error: fmt.Errorf("metric request error: %q", err),
+		}
+		resultChan <- &responseWrapper{
+			DataResponse: &dataResponse,
+		}
 		return nil, err
 	}
 	close(resultChan)