fix: for php8.1

Author: AxiosLeo

src/ArrayMap.php

@@ -277,23 +277,19 @@ public function offsetGet($offset): array
      *
      * @param mixed $offset
      * @param mixed $value
-     *
-     * @return $this
      */
-    public function offsetSet($offset, $value): self
+    public function offsetSet($offset, $value): void
     {
-        return $this->set($offset, $value);
+        $this->set($offset, $value);
     }
 
     /**
      * unset($array[$key]).
      *
      * @param mixed $offset
-     *
-     * @return $this
      */
-    public function offsetUnset($offset): self
+    public function offsetUnset($offset): void
     {
-        return $this->delete($offset);
+        $this->delete($offset);
     }
 }

src/BHDConverter.php

@@ -8,7 +8,6 @@ class BHDConverter
 {
     private $dict;
     private $patch;
-    private $min_length;
 
     public function __construct(
         $dict = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ', // len:62
@@ -17,7 +16,6 @@ public function __construct(
     ) {
         $this->dict       = $dict;
         $this->patch      = $patch;
-        $this->min_length = $min_length;
     }
 
     /**