remove "v2ray.com/core" in log (rebased from 9c1ad3ab93e59a478086083f60b0fe8e3c49faa7)

common/errors/errors.go

@@ -38,6 +38,7 @@ func (err *Error) pkgPath() string {
 		return ""
 	}
 	path := reflect.TypeOf(err.pathObj).PkgPath()
+	//TODO update required on release
 	path = strings.TrimPrefix(path, "github.com/v2fly/v2ray-core/v4/")
 	path = strings.TrimPrefix(path, "github.com/v2fly/v2ray-core/v4")
 	return path