Fix typecheck

Author: ksss

lib/rbs/validator.rb

@@ -13,7 +13,7 @@ def initialize(env:, resolver: nil)
     end
 
     def absolute_type(type, context:, &block)
-      return type unless @resolver
+      return type unless resolver
 
       type.map_type_name do |type_name, _, type|
         resolver.resolve(type_name, context: context) || (block ? yield(type) : type_name)

sig/validator.rbs

@@ -2,15 +2,15 @@ module RBS
   class Validator
     attr_reader env: Environment
 
-    attr_reader resolver: Resolver::TypeNameResolver
+    attr_reader resolver: Resolver::TypeNameResolver?
 
     attr_reader definition_builder: DefinitionBuilder
 
     attr_reader type_alias_dependency: TypeAliasDependency
 
     attr_reader type_alias_regularity: TypeAliasRegularity
 
-    def initialize: (env: Environment, resolver: Resolver::TypeNameResolver) -> void
+    def initialize: (env: Environment, ?resolver: Resolver::TypeNameResolver?) -> void
 
     # Validates the presence of type names and type application arity match.
     #