Don't record the test if initialization fails

When Test.new raises an ArgumentError, nil will be pushed onto the tests
array, and then methods will be called on nil when we iterate over the
tests while building the XML output.

Library/Homebrew/cmd/test-bot.rb

@@ -609,9 +609,9 @@ module Homebrew
           ofail e.message
         else
           test_error = !test.run
+          tests << test
         end
         any_errors ||= test_error
-        tests << test
       end
     end