Correctly handle duplicate named targets

lib/rubysh/command.rb

@@ -53,11 +53,11 @@ def set_stdin(runner, value)
     end
 
     def status(runner)
-      state(runner)[:subprocess].status
+      (subprocess = state(runner)[:subprocess]) ? subprocess.status : nil
     end
 
     def pid(runner)
-      state(runner)[:subprocess].pid
+      (subprocess = state(runner)[:subprocess]) ? subprocess.pid : nil
     end
 
     def prepare!(runner)

test/unit/lib/rubysh/command.rb

@@ -16,5 +16,15 @@ class CommandTest < UnitTest
         assert_equal('Command: ls /tmp 2>&1 /foo', command.to_s)
       end
     end
+
+    describe 'when calling #run_async' do
+      it 'raises the expected error when duplicating a named target' do
+        cmd = Rubysh::Command.new(['ls', '/tmp', Rubysh.>, Rubysh.>])
+        error = assert_raises(Rubysh::Error::BaseError) do
+          cmd.run_async
+        end
+        assert_match(/already has a named target/, error.message)
+      end
+    end
   end
 end