修复并发场景下缓存push操作抛出异常的问题

src/think/cache/Driver.php

@@ -1,4 +1,4 @@
 <?php
 // +----------------------------------------------------------------------
 // | ThinkPHP [ WE CAN DO IT JUST THINK ]
 // +----------------------------------------------------------------------
@@ -117,7 +117,7 @@
         $item = $this->get($name, []);
 
         if (!is_array($item)) {
-            throw new InvalidArgumentException('only array cache can be push');
+            $item = [];
         }
 
         $item[] = $value;