Minor fixes

internal/base/base.go

@@ -7,7 +7,6 @@ package base
 
 import (
 	"context"
-	"errors"
 	"fmt"
 	"sync"
 	"time"
@@ -590,10 +589,3 @@ type Broker interface {
 	PublishCancelation(id string) error
 	Close() error
 }
-
-// List of canonical errors.
-var (
-	ErrNotFound           = errors.New("not found")
-	ErrFailedPrecondition = errors.New("failed precondition")
-	ErrInternal           = errors.New("internal error")
-)