Don't catch exception even if after_response is available

Author: namusyaka

lib/grape/middleware/base.rb

@@ -21,17 +21,13 @@ def call(env)
 
       def call!(env)
         @env = env
-        error_class = nil
         before
         begin
           @app_response = @app.call(@env)
-        rescue => e
-          error_class = e
         ensure
           after_response = after
         end
-
-        after_response || (error_class ? (fail error_class) : @app_response)
+        after_response || @app_response
       end
 
       # @abstract