Fix various bool-type coercions

Author: Girgias

Tests/Iterator/FilecontentFilterIteratorTest.php

@@ -72,7 +72,7 @@ public static function getTestFilterData()
 
         $inner[] = new MockSplFileInfo([
             'name' => 'unreadable-file.txt',
-            'contents' => false,
+            'contents' => '',
             'type' => 'file',
             'mode' => 'r+', ]
         );