When reading Svelte 3 documentation of the {#each} keyword, it isn't clear how to correctly handle the case where the variable we want to iterate on is null or undefined.

A common use case is listing the result of an object of type Promise<MyItem[]>. We could imagine for example that this promise represents the result of an HTTP request. We would first initialized the promise to null as a way to communicate that we didn't fetch any result yet.