Several validator fixes

src/Validator/Rules/DefaultValuesOfCorrectType.php

@@ -6,9 +6,9 @@ use GraphQL\Error;
 use GraphQL\Language\AST\Node;
 use GraphQL\Language\AST\VariableDefinition;
 use GraphQL\Language\Printer;
+use GraphQL\Language\Visitor;
 use GraphQL\Type\Definition\NonNull;
 use GraphQL\Validator\DocumentValidator;
-use GraphQL\Validator\Messages;
 use GraphQL\Validator\ValidationContext;
 
 class DefaultValuesOfCorrectType
@@ -49,8 +49,10 @@ class DefaultValuesOfCorrectType
                         ));
                     }
                 }
-                return null;
-            }
+                return Visitor::skipNode();
+            },
+            Node::SELECTION_SET => function() {return Visitor::skipNode();},
+            Node::FRAGMENT_DEFINITION => function() {return Visitor::skipNode();}
         ];
     }
 }

src/Validator/Rules/UniqueArgumentNames.php

@@ -4,6 +4,7 @@ namespace GraphQL\Validator\Rules;
 use GraphQL\Error;
 use GraphQL\Language\AST\Argument;
 use GraphQL\Language\AST\Node;
+use GraphQL\Language\Visitor;
 use GraphQL\Validator\ValidationContext;
 
 class UniqueArgumentNames
@@ -36,7 +37,7 @@ class UniqueArgumentNames
                 } else {
                     $this->knownArgNames[$argName] = $node->name;
                 }
-                return false;
+                return Visitor::skipNode();
             }
         ];
     }

src/Validator/Rules/UniqueFragmentNames.php

@@ -35,7 +35,7 @@ class UniqueFragmentNames
                 } else {
                     $this->knownFragmentNames[$fragmentName] = $node->name;
                 }
-                return false;
+                return Visitor::skipNode();
             }
         ];
     }

src/Validator/Rules/UniqueOperationNames.php

@@ -34,7 +34,7 @@ class UniqueOperationNames
                         $this->knownOperationNames[$operationName->value] = $operationName;
                     }
                 }
-                return false;
+                return Visitor::skipNode();
             },
             Node::FRAGMENT_DEFINITION => function() {
                 return Visitor::skipNode();