error: Add unwrap (#24)

Add a unwrap func helper

* Unwrap if err is nil then it returns a valid value otherwise it panics

xerror/xerror.go

@@ -0,0 +1,14 @@
+// Copyright 2021 dudaodong@gmail.com. All rights reserved.
+// Use of this source code is governed by MIT license
+
+// Package xerror implements helpers for errors
+package xerror
+
+// Unwrap if err is nil then it returns a valid value
+// If err is not nil, Unwrap panics with err.
+func Unwrap[T any](val T, err error) T {
+	if err != nil {
+		panic(err)
+	}
+	return val
+}