diff --git a/README.md b/README.md
index f8bb2ce..08bac06 100644
--- a/README.md
+++ b/README.md
@@ -25,13 +25,13 @@ import "github.com/arshamalh/twigo"
 
 twigo.NewClient((&twigo.Config{
   ConsumerKey:    "ConsumerKey",
-	ConsumerSecret: "ConsumerSecret",
-	AccessToken:    "AccessToken",
-	AccessSecret:   "AccessTokenSecret",
+  ConsumerSecret: "ConsumerSecret",
+  AccessToken:    "AccessToken",
+  AccessSecret:   "AccessTokenSecret",
   // Both of "bearer token" or "four other keys (ConsumerKey, ...)" is not mandatory.
   // We'll find bearer token automatically if it's not specified.
   // Also, you can use twigo.utils.BearerFinder() function.
-	BearerToken:    "BearerToken",
+  BearerToken:    "BearerToken",
 }))
 ```
 
diff --git a/client.go b/client.go
index c50025d..a6b2f4b 100644
--- a/client.go
+++ b/client.go
@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"net/http"
 	"net/url"
+	"strings"
 
 	"github.com/arshamalh/twigo/utils"
 )
@@ -71,7 +72,14 @@ func (c *Client) get_request(route string, oauth_type OAuthType, params Map, end
 
 		request.Header.Set("Authorization", fmt.Sprintf("Bearer %s", c.bearerToken))
 		client := http.Client{}
-		return client.Do(request)
+		resp, err := client.Do(request)
+		if resp.StatusCode != 200 {
+			err := SpecialError{}
+			json.NewDecoder(resp.Body).Decode(&err)
+			defer resp.Body.Close()
+			return nil, err.Error()
+		}
+		return resp, err
 	}
 }
 
@@ -1118,6 +1126,7 @@ func (c *Client) GetUserByUsername(username string, params Map) (*UserResponse,
 	endpoint_parameters := []string{
 		"expansions", "tweet.fields", "user.fields",
 	}
+	username = strings.Replace(username, "@", "", 1)
 	route := fmt.Sprintf("users/by/username/%s", username)
 	response, err := c.get_request(route, c.oauth_type, params, endpoint_parameters)
 	if err != nil {
@@ -1154,6 +1163,8 @@ func (c *Client) GetUsersByIDs(user_ids []string, params Map) (*UsersResponse, e
 // Returns a variety of information about one or more users specified by
 // the requested usernames.
 //
+// usernames should not have @ at the beginning
+//
 // https://developer.twitter.com/en/docs/twitter-api/users/lookup/api-reference/get-users-by
 func (c *Client) GetUsersByUsernames(usernames []string, params Map) (*UsersResponse, error) {
 	endpoint_parameters := []string{
diff --git a/entities.go b/entities.go
index fbfadd0..19b7ade 100644
--- a/entities.go
+++ b/entities.go
@@ -1,6 +1,7 @@
 package twigo
 
 import (
+	"fmt"
 	"net/http"
 	"strconv"
 	"time"
@@ -22,6 +23,17 @@ type ErrorEntity struct {
 	Message    string                 `json:"message"`
 }
 
+type SpecialError struct {
+	Title  string `json:"title"`
+	Type   string `json:"type"`
+	Status int    `json:"status"`
+	Detail string `json:"detail"`
+}
+
+func (e *SpecialError) Error() error {
+	return fmt.Errorf("%s - %d - %s - %s", e.Title, e.Status, e.Type, e.Detail)
+}
+
 type IncludesEntity struct {
 	Users  []entities.User  `json:"users"`
 	Tweets []entities.Tweet `json:"tweets"`
diff --git a/twigo.go b/twigo.go
index 8672cb3..f2ffd26 100644
--- a/twigo.go
+++ b/twigo.go
@@ -1,7 +1,6 @@
 package twigo
 
 import (
-	"fmt"
 	"strings"
 
 	"github.com/arshamalh/twigo/utils"
@@ -21,7 +20,11 @@ func NewClient(config *Config) (*Client, error) {
 
 	if !keys_exists {
 		if config.BearerToken == "" {
-			return nil, fmt.Errorf("consumer key, consumer secret, access token and access token secret must be provided")
+			if bearer_token, err := utils.BearerFinder(config.ConsumerKey, config.ConsumerSecret); err == nil {
+				config.BearerToken = bearer_token
+			} else {
+				return nil, err
+			}
 		}
 
 		userID := ""
@@ -31,10 +34,10 @@ func NewClient(config *Config) (*Client, error) {
 
 		return &Client{
 			nil,
-			config.ConsumerKey,
-			config.ConsumerSecret,
-			config.AccessToken,
-			config.AccessSecret,
+			"",
+			"",
+			"",
+			"",
 			config.BearerToken,
 			true,
 			userID,
@@ -42,14 +45,6 @@ func NewClient(config *Config) (*Client, error) {
 		}, nil
 	}
 
-	if config.BearerToken == "" {
-		if bearer_token, err := utils.BearerFinder(config.ConsumerKey, config.ConsumerSecret); err == nil {
-			config.BearerToken = bearer_token
-		} else {
-			return nil, err
-		}
-	}
-
 	userID := strings.Split(config.AccessToken, "-")[0]
 
 	// TODO: I'm authenticating here, but Do I need to authenticate every once in a while?