fix typo (#1004)

* 修改拼写错误

修改拼写错误
exsits -> exists

* Update router_login.go

src/webapi/router/router_login.go

@@ -143,8 +143,8 @@ func refreshPost(c *gin.Context) {
 func loginRedirect(c *gin.Context) {
 	redirect := ginx.QueryStr(c, "redirect", "/")
 
-	v, exsits := c.Get("userid")
-	if exsits {
+	v, exists := c.Get("userid")
+	if exists {
 		userid := v.(int64)
 		user, err := models.UserGetById(userid)
 		ginx.Dangerous(err)
@@ -152,7 +152,7 @@ func loginRedirect(c *gin.Context) {
 			ginx.Bomb(200, "user not found")
 		}
 
-		if user.Username != "" { // alread login
+		if user.Username != "" { // already login
 			ginx.NewRender(c).Data(redirect, nil)
 			return
 		}