Removing unused error variable from tree.
diff --git a/cmd/tree.go b/cmd/tree.go
index 0a276fd..377aba1 100644
--- a/cmd/tree.go
+++ b/cmd/tree.go
@@ -1,7 +1,6 @@
 package cmd
 
 import (
-	"errors"
 	"fmt"
 	"os"
 	"path/filepath"
@@ -11,8 +10,6 @@
 	"github.com/Masterminds/cookoo"
 )
 
-var ErrPkgNotFound = errors.New("package not found")
-
 // Tree prints a tree representing dependencies.
 func Tree(c cookoo.Context, p *cookoo.Params) (interface{}, cookoo.Interrupt) {
 	buildContext, err := GetBuildContext()