diff --git a/core/installer/app.go b/core/installer/app.go
index d7f6989..1bf632c 100644
--- a/core/installer/app.go
+++ b/core/installer/app.go
@@ -255,8 +255,8 @@
 		return cue.Value{}, fmt.Errorf("invalid")
 	}
 	ret := ctx.BuildInstance(instances[0])
-	if ret.Err() != nil {
-		return cue.Value{}, ret.Err()
+	if err := ret.Err(); err != nil {
+		return cue.Value{}, err
 	}
 	if err := ret.Validate(); err != nil {
 		return cue.Value{}, err