TopLevelSchemaLinkProviderBase::getLink breaks on custom route

I created a route which serializes an entity to a JSON:API argument. This worked great until I installed JSON:API Schema.

This is due to the route generation to try and create the describedby link

    else {
      $resource_type_name = explode('.', $this->currentRouteMatch->getRouteName())[1];
      $schema_route_name = "jsonapi_schema.{$resource_type_name}." . static::$schemaRouteType;
    }

In my case the route was called mymodule_jsonapi.json_view. This returned the rendered JSON in a modal.

The code in JSON:API Schema caused this route to fail as it tried to look up a route called jsonapi_schema.json_view.item, which is not a valid route. All JSON:API routes should have resource_type in their route per

    // Add the resource type as a parameter to every resource route.
    foreach ($routes as $route) {
      static::addRouteParameter($route, static::RESOURCE_TYPE_KEY, ['type' => ResourceTypeConverter::PARAM_TYPE_ID]);
      $route->addDefaults([static::RESOURCE_TYPE_KEY => $resource_type->getTypeName()]);
    }

So maybe we could fetch that from the route if it exists versus magically grabbing it from the route name.