Added missing typehint

Author: GrahamCampbell

src/Loader/Loader.php

@@ -87,7 +87,7 @@ private function processEntries(RepositoryInterface $repository, array $entries)
     private static function resolveNestedVariables(RepositoryInterface $repository, Value $value = null)
     {
         return Option::fromValue($value)
-            ->map(function ($v) use ($repository) {
+            ->map(function (Value $v) use ($repository) {
                 return array_reduce($v->getVars(), function ($s, $i) use ($repository) {
                     return substr($s, 0, $i).self::resolveNestedVariable($repository, substr($s, $i));
                 }, $v->getChars());