Fixed compatibility issue with ArrayAccess in htmldoc.php.

Author: hexydec

src/htmldoc.php

@@ -117,7 +117,7 @@ public function offsetUnset($i) : void {
 	 * @param string|integer $i The key to be accessed, can be a string or integer
 	 * @return mixed The requested value or null if the key doesn't exist
 	 */
-	public function offsetGet($i) { // return reference so you can set it like an array
+	public function offsetGet(mixed $i) : mixed { // return reference so you can set it like an array
 		return $this->children[$i] ?? null;
 	}
 
@@ -126,7 +126,7 @@ public function offsetGet($i) { // return reference so you can set it like an ar
 	 *
 	 * @return tag|text|comment|doctype The child node at the current pointer position
 	 */
-	public function current() {
+	public function current() : mixed {
 		return $this->children[$this->pointer] ?? null;
 	}