SCIM API errors: NoMethodError: undefined method `each' for #<String:0x00007fa30e7c13a8>

https://sentry.gitlab.net/gitlab/gitlabcom/issues/4065492/?referrer=gitlab_plugin

NoMethodError: undefined method `status' for nil:NilClass
  lib/api/api_guard.rb:215:in `call'
    response = super(env)
  lib/gitlab/metrics/elasticsearch_rack_middleware.rb:16:in `call'
    @app.call(env)
  lib/gitlab/middleware/memory_report.rb:13:in `call'
    return @app.call(env) unless rendering_memory_profiler?(request)
  lib/gitlab/middleware/speedscope.rb:13:in `call'
    return @app.call(env) unless rendering_flamegraph?(request)
  lib/gitlab/database/load_balancing/rack_middleware.rb:23:in `call'
    result = @app.call(env)
...
(155 additional frame(s) were not displayed)

NoMethodError: undefined method `preferred_language' for #<Rack::Response:0x00007fa30e7c1ee8>
  lib/api/helpers.rb:79:in `current_user'
    Gitlab::I18n.locale = @current_user&.preferred_language
  lib/api/helpers.rb:538:in `handle_api_exception'
    Gitlab::ApplicationContext.push(user: current_user, remote_ip: request.ip)
  lib/api/api.rb:138:in `block in <class:API>'
    handle_api_exception(exception)
  lib/gitlab/metrics/elasticsearch_rack_middleware.rb:16:in `call'
    @app.call(env)
  lib/gitlab/middleware/memory_report.rb:13:in `call'
    return @app.call(env) unless rendering_memory_profiler?(request)
...
(134 additional frame(s) were not displayed)

NoMethodError: undefined method `each' for #<String:0x00007fa30e7c13a8>
  lib/gitlab/grape_logging/loggers/response_logger.rb:11:in `parameters'
    response.each { |resp| response_bytes += resp.to_s.bytesize }
  lib/gitlab/metrics/elasticsearch_rack_middleware.rb:16:in `call'
    @app.call(env)
  lib/gitlab/middleware/memory_report.rb:13:in `call'
    return @app.call(env) unless rendering_memory_profiler?(request)
  lib/gitlab/middleware/speedscope.rb:13:in `call'
    return @app.call(env) unless rendering_flamegraph?(request)
  lib/gitlab/database/load_balancing/rack_middleware.rb:23:in `call'
    result = @app.call(env)
...
(134 additional frame(s) were not displayed)