fix 修改设置前缀问题

ruoyi-system-file/src/main/java/com/ruoyi/file/FileService.java

@@ -166,7 +166,7 @@ public interface FileService {
    */
   default FileService setPrefix(String prefix) {
     if (StrUtil.isBlank(prefix)) {
-      throw new RuntimeException("路径前缀不能为空");
+      return this;
     }
     if (!prefix.matches("^[\\w\\-]+$")) {
       throw new RuntimeException("路径前缀规则错误");