Uninitialized variable warnings

[walro]

/Users/robin/.gem/ruby/2.4.4/gems/twingly-search-5.1.4/lib/twingly/search/query.rb:80: warning: instance variable @language not initialized
/Users/robin/.gem/ruby/2.4.4/gems/twingly-search-5.1.4/lib/twingly/search/query.rb:39: warning: instance variable @start_time not initialized
/Users/robin/.gem/ruby/2.4.4/gems/twingly-search-5.1.4/lib/twingly/search/query.rb:44: warning: instance variable @end_time not initialized