check bundler is present before using it

Author: technicalpickles

lib/singed/cli.rb

@@ -88,11 +88,19 @@ def run
         prompt_password
       end
 
-      Bundler.with_unbundled_env do
+      rbspy = lambda do
         # don't run things with spring, because it forks and rbspy won't see it
         sudo ['rbspy', *rbspy_args], reason: 'Singed needs to run as root, but will drop permissions back to your user.', env: { 'DISABLE_SPRING' => '1' }
       end
 
+      if defined?(Bundler)
+        Bundler.with_unbundled_env do
+          rbspy.call
+        end
+      else
+        rbspy.call
+      end
+
       unless filename.exist?
         puts "#{filename} doesn't exist. Maybe rbspy had a failure capturing it? Check the scrollback."
         exit 1