Possible fix for this exception that happens in production for unclear
reasons:
NoMethodError: undefined method `is_admin?' for nil:NilClass
…oru/releases/20200805193154/app/policies/tag_policy.rb: 3:in `can_change_category?'
…www/danbooru/releases/20200805193154/app/models/tag.rb: 216:in `find_or_create_by_name'
…www/danbooru/releases/20200805193154/app/models/tag.rb: 193:in `block in create_for_list'
…www/danbooru/releases/20200805193154/app/models/tag.rb: 193:in `map'
…www/danbooru/releases/20200805193154/app/models/tag.rb: 193:in `create_for_list'
…ww/danbooru/releases/20200805193154/app/models/post.rb: 463:in `normalize_tags'