Fix inconsistent return points.

Author: derrabus

Generator/UrlGenerator.php

@@ -123,6 +123,8 @@ public function generate($name, $parameters = [], $referenceType = self::ABSOLUT
      * @throws MissingMandatoryParametersException When some parameters are missing that are mandatory for the route
      * @throws InvalidParameterException           When a parameter value for a placeholder is not correct because
      *                                             it does not match the requirement
+     *
+     * @return string|null
      */
     protected function doGenerate($variables, $defaults, $requirements, $tokens, $parameters, $name, $referenceType, $hostTokens, array $requiredSchemes = [])
     {
@@ -150,7 +152,7 @@ protected function doGenerate($variables, $defaults, $requirements, $tokens, $pa
                             $this->logger->error($message, ['parameter' => $token[3], 'route' => $name, 'expected' => $token[2], 'given' => $mergedParams[$token[3]]]);
                         }
 
-                        return;
+                        return null;
                     }
 
                     $url = $token[1].$mergedParams[$token[3]].$url;
@@ -205,7 +207,7 @@ protected function doGenerate($variables, $defaults, $requirements, $tokens, $pa
                             $this->logger->error($message, ['parameter' => $token[3], 'route' => $name, 'expected' => $token[2], 'given' => $mergedParams[$token[3]]]);
                         }
 
-                        return;
+                        return null;
                     }
 
                     $routeHost = $token[1].$mergedParams[$token[3]].$routeHost;

Generator/UrlGeneratorInterface.php

@@ -75,7 +75,7 @@ interface UrlGeneratorInterface extends RequestContextAwareInterface
      * @param mixed[] $parameters    An array of parameters
      * @param int     $referenceType The type of reference to be generated (one of the constants)
      *
-     * @return string The generated URL
+     * @return string|null The generated URL
      *
      * @throws RouteNotFoundException              If the named route doesn't exist
      * @throws MissingMandatoryParametersException When some parameters are missing that are mandatory for the route

Matcher/Dumper/StaticPrefixCollection.php

@@ -114,7 +114,7 @@ private function groupWithItem($item, $prefix, $route)
         $commonPrefix = $this->detectCommonPrefix($prefix, $itemPrefix);
 
         if (!$commonPrefix) {
-            return;
+            return null;
         }
 
         $child = new self($commonPrefix);

Matcher/TraceableUrlMatcher.php

@@ -127,6 +127,8 @@ protected function matchCollection($pathinfo, RouteCollection $routes)
 
             return true;
         }
+
+        return [];
     }
 
     private function addTrace($log, $level = self::ROUTE_DOES_NOT_MATCH, $name = null, $route = null)