Fix loginform issue

Author: Thomas

server/api-service/lowcoder-server/src/main/java/org/lowcoder/api/authentication/service/AuthenticationApiServiceImpl.java

@@ -225,7 +225,7 @@ public void updateConnection(AuthUser authUser, User user) {
         oldConnection.setRawUserInfo(authUser.getRawUserInfo());
 
         //if auth by google, set refresh token
-        if (StringUtils.isEmpty(authUser.getAuthToken().getRefreshToken()) && StringUtils.isNotEmpty(oldConnection.getAuthConnectionAuthToken().getRefreshToken())) {
+        if (authUser.getAuthToken()!=null && oldConnection.getAuthConnectionAuthToken()!=null && StringUtils.isEmpty(authUser.getAuthToken().getRefreshToken()) && StringUtils.isNotEmpty(oldConnection.getAuthConnectionAuthToken().getRefreshToken())) {
             authUser.getAuthToken().setRefreshToken(oldConnection.getAuthConnectionAuthToken().getRefreshToken());
         }