[monaco-graphql] hover broken

### Is there an existing issue for this? - [x] I have searched the existing issues ### Current Behavior If you hover at the beginning of the query editor, it shows an error `Error: Expected Parser stream to be available` I believe this can easily be fixed in the GraphQLWorker file -> doHover function by changing to return early ``` const hover = this._languageService.getHover(uri, document, graphQLPosition); if (!hover) return; ``` Not sure if this may be related to #3168 from a few years ago or not. ### Expected Behavior Should not throw `Error: Expected Parser stream to be available` in the UI console. ### Steps To Reproduce To reproduce go to the swapi or netlify demos from the graphiql docs, open the UI console, and hover at position 0. <img width="1573" height="412" alt="Image" src="https://github.com/user-attachments/assets/57dd6655-89b9-4dba-a8ca-f211a726c7df" /> <img width="1120" height="309" alt="Image" src="https://github.com/user-attachments/assets/a9fcbae8-49e3-40e7-ac0c-0a564e150e0f" /> ### Environment * GraphiQL Version: 5.2.2 * OS: Mac Sequoia 15.7.3 (24G419) * Browser: Chrome * Bundler: tried with vite and esbuild and the demos * `react` Version: 16.12 * `graphql` Version: 18.2 ### Anything else? _No response_