删除一个空指针异常问题

pdf-tech-core/src/main/java/cn/kdan/pdf/tech/core/service/impl/VppKeyFileServiceImpl.java

@@ -38,7 +38,7 @@ public class VppKeyFileServiceImpl implements VppKeyFileService {
         try (InputStream inputStream = keyFile.getInputStream()) {
             fileContent = KeyFileParseUtils.parseKeyFile(inputStream, updateOrInit);
         } catch (Exception e) {
-            log.error("解析key文件失败, ".concat(e.getMessage()), e);
+            log.error("解析key文件失败, "+ e.getMessage(), e);
             throw new RuntimeException("The key file signature is invalid.");
         }
         if (!updateOrInit) {