Plugins: Use error plane for api/ds/query (#54750)

* plugin client returns error base

* fix api test

* add plugin client test

* add fallback err

* fix linting

* wip

* replace bad query

* template is an error

* failing test of templated error

* add one test passing

* fix failing test

* move test

* rename ErrBadQuery to ErrQueryValidationFailure

* tidy diff

* Change to one error per specific error kind

* last err + fix test

* fix imports

* more tests

* keep req vars together

Co-authored-by: Marcus Efraimsson <marcus.efraimsson@gmail.com>

pkg/util/errutil/errors.go

@@ -166,12 +166,16 @@ func (e Error) Is(other error) bool {
 	o, isGrafanaError := other.(Error)
 	//nolint:errorlint
 	base, isBase := other.(Base)
+	//nolint:errorlint
+	templateErr, isTemplateErr := other.(Template)
 
 	switch {
 	case isGrafanaError:
 		return o.Reason == e.Reason && o.MessageID == e.MessageID && o.Error() == e.Error()
 	case isBase:
 		return base.Is(e)
+	case isTemplateErr:
+		return templateErr.Base.Is(e)
 	default:
 		return false
 	}

pkg/util/errutil/template.go

@@ -115,3 +115,7 @@ func (t Template) Build(data TemplateData) error {
 
 	return e
 }
+
+func (t Template) Error() string {
+	return t.Base.Error()
+}

pkg/util/errutil/template_test.go

@@ -3,10 +3,30 @@ package errutil_test
 import (
 	"errors"
 	"fmt"
+	"testing"
 
 	"github.com/grafana/grafana/pkg/util/errutil"
+	"github.com/stretchr/testify/require"
 )
 
+func TestTemplate(t *testing.T) {
+	tmpl := errutil.NewBase(errutil.StatusInternal, "template.sample-error").MustTemplate("[{{ .Public.user }}] got error: {{ .Error }}")
+	err := tmpl.Build(errutil.TemplateData{
+		Public: map[string]interface{}{
+			"user": "grot the bot",
+		},
+		Error: errors.New("oh noes"),
+	})
+
+	t.Run("Built error should return true when compared with templated error ", func(t *testing.T) {
+		require.True(t, errors.Is(err, tmpl))
+	})
+
+	t.Run("Built error should return true when compared with templated error base ", func(t *testing.T) {
+		require.True(t, errors.Is(err, tmpl.Base))
+	})
+}
+
 func ExampleTemplate() {
 	// Initialization, this is typically done on a package or global
 	// level.