[10.x] Add keys length check to prevent mget error (#46998)

* [10.x] Add keys length check to prevent mget error

* [10.x] changed formatting to comply with PR standard

---------

Co-authored-by: Tristan ter Haar <[email protected]>

Author: tloader11

src/Illuminate/Cache/RedisStore.php

@@ -77,6 +77,10 @@ public function get($key)
      */
     public function many(array $keys)
     {
+        if (count($keys) === 0) {
+            return [];
+        }
+
         $results = [];
 
         $values = $this->connection()->mget(array_map(function ($key) {