get_userlists methods fail with NoMethodError when user does not exist

[elifoster]

b.get_userlists('editcount', 'asduahsdaiushduaihsd')
# => {"batchcomplete"=>"", "query"=>{"users"=>[{"name"=>"Asduahsdaiushduaihsd", "missing"=>""}]}}
b.get_userlists('editcount', 'TheSatanicSanta')
# => {"batchcomplete"=>"", "query"=>{"users"=>[{"userid"=>39314627, "name"=>"TheSatanicSanta", "editcount"=>34172}]}}

The userlist methods do not check if the missing key is present, causing a NoMethodError:

b.get_contrib_count('asduahsdaiushduaihsd')
# NoMethodError: undefined method `[]' for nil
# from .../ruby/gems/3.3.0/gems/mediawiki-butt-4.0.1/lib/mediawiki/query/lists/users.rb:80:in `get_contrib_count'