error: Add unwrap (#24)

Add a unwrap func helper

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

README.md

@@ -588,3 +588,29 @@ func IsIpV6(ipstr string) bool //check if the string is a ipv6 address
 func IsStrongPassword(password string, length int) bool //check if the string is strong password (alpha(lower+upper) + number + special chars(!@#$%^&*()?><))
 func IsWeakPassword(password string) bool //check if the string is weak password（only letter or only number or letter + number）
 ```
+
+### 14. error helpers
+
+- Contain functions to handle errors
+- Usage: import "github.com/duke-git/lancet/xerror"
+
+```go
+package main
+
+import (
+    "fmt"
+    "io/ioutil"
+    "log"
+    "github.com/duke-git/lancet/errors"
+)
+
+func main() {
+	x := Unwrap(strconv.Atoi("42")) // Unwrap if err is nil then it returns a valid value otherwise it panics
+}
+```
+
+- Function list:
+
+```go
+Unwrap[T any](val T, err error)
+```

README_zh-CN.md

@@ -589,3 +589,29 @@ func IsIpV6(ipstr string) bool //判断字符串是否是ipv6
 func IsStrongPassword(password string, length int) bool //判断字符串是否是强密码（大小写字母+数字+特殊字符）
 func IsWeakPassword(password string) bool //判断字符串是否是弱密码（只有字母或数字）
 ```
+
+### 14. error helpers
+
+- Contain functions to handle errors
+- Usage: import "github.com/duke-git/lancet/xerror"
+
+```go
+package main
+
+import (
+    "fmt"
+    "io/ioutil"
+    "log"
+    "github.com/duke-git/lancet/errors"
+)
+
+func main() {
+	x := Unwrap(strconv.Atoi("42")) 
+}
+```
+
+- Function list:
+
+```go
+Unwrap[T any](val T, err error)
+```

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
+}

xerror/xerror_test.go

@@ -0,0 +1,24 @@
+package xerror
+
+import (
+	"github.com/duke-git/lancet/internal"
+	"strconv"
+	"testing"
+)
+
+func TestUnwrap(t *testing.T) {
+	assert := internal.NewAssert(t, "TestUnwrap")
+	assert.Equal(42, Unwrap(strconv.Atoi("42")))
+}
+
+func TestUnwrapFail(t *testing.T) {
+	assert := internal.NewAssert(t, "TestUnwrapFail")
+
+	_, err := strconv.Atoi("4o2")
+	defer func() {
+		v := recover()
+		assert.Equal(err.Error(), v.(*strconv.NumError).Error())
+	}()
+
+	Unwrap(strconv.Atoi("4o2"))
+}