fix for #99

TagTrait.patch

diff --git a/src/*/AppBundle/Entity/TagTrait.php b/src/*/AppBundle/Entity/TagTrait.php
index 2024712..d7d2465 100644
--- a/src/*/AppBundle/Entity/TagTrait.php
+++ b/src/*/AppBundle/Entity/TagTrait.php
@@ -62,6 +62,6 @@ trait TagTrait
 
     public function __toString()
     {
-        return ($this->getValue()) ? : '';
+        return (is_null($this->getValue())) ? '' : $this->getValue();
     }
 }