How to migrate loaders that use "getOrThrow"?

[PaulRBerg]

The Migrating from Loaders section in the docs does not explain how to migrate getOrThrow loaders.

If I use them like this:

const handler: Handler = async ({ context, event }) => {
  const streamId = Id.stream(event.srcAddress, event.chainId, event.params.tokenId);
  const watcherId = event.chainId.toString();

  const [stream, watcher] = await Promise.all([
    context.Stream.getOrThrow(streamId),
    context.Watcher.getOrThrow(watcherId),
  ]);

  if (context.isPreload) {
    return;
  }

I am getting errors like this:

"type": "Error",
     "message": "Entity 'Stream' with ID '0x556d859dfeb58ed3fa092b6526b09da6b74113e2-999-1' is expected to exist.",
     "stack":
         Error: Entity 'Stream' with ID '0x556d859dfeb58ed3fa092b6526b09da6b74113e2-999-1' is expected to exist.

But I use get instead of getOrThrow, then I have to re-add manual null checks for my entities.

1. Are getOrThrow functions not meant to be used with Preload Optimization?
2. If that is so, are we meant to add null checks?

@DZakh

[PaulRBerg]

Nevermind, false positive

This was the NFT transfer function. Had to exclude mints