Chore: Enable errorlint linter (#29227)

* Enable errorlint linter
* Handle wrapped errors

Signed-off-by: Arve Knudsen <arve.knudsen@gmail.com>
Co-authored-by: Emil Tullstedt <emil.tullstedt@grafana.com>

pkg/cmd/grafana-cli/services/api_client.go

@@ -4,6 +4,7 @@ import (
 	"bufio"
 	"crypto/md5"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io"
 	"io/ioutil"
@@ -25,9 +26,8 @@ type GrafanaComClient struct {
 func (client *GrafanaComClient) GetPlugin(pluginId, repoUrl string) (models.Plugin, error) {
 	logger.Debugf("getting plugin metadata from: %v pluginId: %v \n", repoUrl, pluginId)
 	body, err := sendRequestGetBytes(HttpClient, repoUrl, "repo", pluginId)
-
 	if err != nil {
-		if err == ErrNotFoundError {
+		if errors.Is(err, ErrNotFoundError) {
 			return models.Plugin{}, errutil.Wrap("Failed to find requested plugin, check if the plugin_id is correct", err)
 		}
 		return models.Plugin{}, errutil.Wrap("Failed to send request", err)

pkg/cmd/grafana-cli/services/api_client_test.go

@@ -2,6 +2,7 @@ package services
 
 import (
 	"bytes"
+	"errors"
 	"io"
 	"io/ioutil"
 	"net/http"
@@ -74,8 +75,9 @@ func makeBody(body string) io.ReadCloser {
 }
 
 func asBadRequestError(t *testing.T, err error) *BadRequestError {
-	if badRequestError, ok := err.(*BadRequestError); ok {
-		return badRequestError
+	var badErr *BadRequestError
+	if errors.As(err, &badErr) {
+		return badErr
 	}
 	assert.FailNow(t, "Error was not of type BadRequestError")
 	return nil