Fix master for release : Type error in TagImg

library/ZendAfi/View/Helper/TagImg.php

@@ -21,7 +21,7 @@
 
 class ZendAfi_View_Helper_TagImg extends ZendAfi_View_Helper_BaseHelper {
 
-  public function tagImg(string $url, array $attribs = []) : string {
+  public function tagImg(?string $url, array $attribs = []) : string {
     if ( ! $url)
       return '';