in src/azure/AzureHttpTriggerPlugin.ts [80:91]
      context.done = function (err: any, _ret: any) {
        if (!did) {
          if (err) span.error(err);
          if (arguments.length >= 2) arguments[1] = stop(_ret);
          else stop();
          did = true;
        }
        return done.apply(this, arguments);
      };