fixed (and now with tests) false/null confusion

src/Symfony/Bundle/DoctrineBundle/Request/ParamConverter/DoctrineConverter.php

@@ -43,9 +43,9 @@ class DoctrineConverter implements ConverterInterface
         $class = $parameter->getClass()->getName();
 
         // find by identifier?
-        if (null === $object = $this->find($class, $request)) {
+        if (false === $object = $this->find($class, $request)) {
             // find by criteria
-            if (null === $object = $this->findOneBy($class, $request)) {
+            if (false === $object = $this->findOneBy($class, $request)) {
                 throw new \LogicException('Unable to guess how to get a Doctrine instance from the request information.');
             }
         }
@@ -60,7 +60,7 @@ class DoctrineConverter implements ConverterInterface
     protected function find($class, Request $request)
     {
         if (!$request->attributes->has('id')) {
-            return null;
+            return false;
         }
 
         return $this->manager->getRepository($class)->find($request->attributes->get('id'));
@@ -77,7 +77,7 @@ class DoctrineConverter implements ConverterInterface
         }
 
         if (!$criteria) {
-            return null;
+            return false;
         }
 
         return $this->manager->getRepository($class)->findOneBy($criteria);