trade 2 is_a? checks for a nil check

1 files changed, 4 insertions, 2 deletions

diff --git a/actionpack/lib/action_dispatch/routing/mapper.rb b/actionpack/lib/action_dispatch/routing/mapper.rb
index e8dd54b3f0..528bcd4189 100644
--- a/actionpack/lib/action_dispatch/routing/mapper.rb
+++ b/actionpack/lib/action_dispatch/routing/mapper.rb
@@ -293,11 +293,13 @@ module ActionDispatch
               raise ArgumentError, message
             end
 
-            if controller.is_a?(String) && controller =~ %r{\A/}
+            return unless controller
+
+            if controller =~ %r{\A/}
               raise ArgumentError, "controller name should not start with a slash"
             end
 
-            if controller.is_a?(String) && controller !~ /\A[a-z_0-9\/]*\z/
+            if controller !~ /\A[a-z_0-9\/]*\z/
               message = "'#{controller}' is not a supported controller name. This can lead to potential routing problems."
               message << " See http://guides.rubyonrails.org/routing.html#specifying-a-controller-to-use"
               raise ArgumentError, message