Use dedicated exceptions if unlinking failed for reasons other than the

file not existing

exceptions/MDFilePermissionsException.php

@@ -0,0 +1,18 @@
+<?PHP
+declare(strict_types = 1);
+
+/**
+ * Reports a failure due to insufficient permissions in the file system.
+ */
+final class MDFilePermissionsException extends Exception {
+    /**
+     * Error message.
+     *
+     * @return string
+     */
+    public function errorMessage() {
+        //error message
+        return 'Insufficient file system permissions';
+
+    }
+}