fix(测试跟踪): 用例脑图保存报错

--bug=1018924 --user=陈建星 【测试跟踪】测试用例-脑图-编辑-保存报500 https://www.tapd.cn/55049933/s/1278354

test-track/backend/src/main/java/io/metersphere/service/TestCaseService.java

@@ -439,6 +439,9 @@ public class TestCaseService {
      * @param testCase
      */
     private void createNewVersionOrNot(EditTestCaseRequest testCase) {
+        if (StringUtils.isBlank(testCase.getVersionId())) {
+            return;
+        }
         TestCaseExample example = new TestCaseExample();
         example.createCriteria().andIdEqualTo(testCase.getId())
                 .andVersionIdEqualTo(testCase.getVersionId());