Fix error logs/message for loki-op 6

We're seeing a lot of errors with "no message found". This is because
with Loki operator 6, the json of the error has changed. We need now to
look at the "error" field.

Also add more debug logs

Author: jotak

pkg/handler/loki.go

@@ -101,9 +101,13 @@ func getLokiError(resp []byte, code int) (int, string) {
 		hlog.WithError(err).Errorf("cannot unmarshal, response was: %v", string(resp))
 		return http.StatusBadRequest, fmt.Sprintf("Unknown error from Loki\ncannot unmarshal\n%s", resp)
 	}
-	message, ok := f["message"]
+	message, ok := f["error"]
 	if !ok {
-		return http.StatusBadRequest, "Unknown error from Loki\nno message found"
+		message, ok = f["message"]
+		if !ok {
+			hlog.WithError(err).Errorf("unknown Loki error: %v", f)
+			return http.StatusBadRequest, "Unknown error from Loki"
+		}
 	}
 	return http.StatusBadRequest, fmt.Sprintf("Loki message: %s", message)
 }
@@ -135,6 +139,7 @@ func executeLokiQuery(flowsURL string, lokiClient httpclient.Caller) ([]byte, in
 	}
 	if code != http.StatusOK {
 		newCode, msg := getLokiError(resp, code)
+		hlog.Debugf("executeLokiQuery error: [%d] %s", code, msg)
 		return nil, newCode, fmt.Errorf("Error from Loki query: [%d] %s", code, msg)
 	}
 	return resp, http.StatusOK, nil
@@ -151,6 +156,7 @@ func getLokiLabelValues(baseURL string, lokiClient httpclient.Caller, label stri
 	}
 	if code != http.StatusOK {
 		newCode, msg := getLokiError(resp, code)
+		hlog.Debugf("getLokiLabelValues error: [%d] %s", code, msg)
 		return nil, newCode, errors.New(msg)
 	}
 	hlog.Tracef("getLokiLabelValues raw response: %s", resp)