tweak: static analysis improvements

Author: g105b

src/Path/FileMatch/FileMatch.php

@@ -34,7 +34,10 @@ public function __construct(
 		}
 	}
 
-	/** @param null|array<string> $siblingFiles */
+	/**
+	 * @param null|array<string> $siblingFiles
+	 * @return array<string>
+	 */
 	private function getSiblingFiles(?array $siblingFiles):array {
 		if($siblingFiles !== null) {
 			return $siblingFiles;