[relay-lsp] Fails to start with incomplete executable document

If your code contains some invalid graphql tagged literal like:

```ts
const query = graphql`query`
```

And you restart the Relay LSP, you always get the following LSP error on hover, complete, etc.

> get_schema: schema is missing (or not ready, yet) for the `default` project

Once you remove or properly write out the offending graphql tagged literal everything works again.

I would expect the LSP to just skip over such incomplete definitions at startup instead of just failing.