chore(oauth2): add oauth2 error parse

Author: duanhongyi

errors.go

@@ -140,6 +140,15 @@ func checkForErrors(res *http.Response) error {
 			return unknownServerError(res.StatusCode, string(out))
 		}
 
+		if oauthErr, ok := bodyMap["error"].(string); ok {
+			if oauthErr == "invalid_grant" {
+				return ErrLogin
+			}
+			if desc, ok := bodyMap["error_description"].(string); ok && desc != "" {
+				return unknownServerError(res.StatusCode, desc)
+			}
+		}
+
 		if scanResponse(bodyMap, "username", []string{fieldReqMsg, invalidUserMsg}, true) {
 			return ErrInvalidUsername
 		}

errors_test.go

@@ -96,6 +96,13 @@ func TestErrors(t *testing.T) {
 			},
 			expected: ErrLogin,
 		},
+		{
+			res: &http.Response{
+				StatusCode: 400,
+				Body:       readCloser(`{"error": "invalid_grant", "error_description": "Invalid credentials given."}`),
+			},
+			expected: ErrLogin,
+		},
 		{
 			res: &http.Response{
 				StatusCode: 400,