VS Code extension throws on launch if Q# notebook cell is open

[minestarks]

Repro

1. Create a notebook like so - with one cell with language set to "Q#" but no %%qsharp magic

2. Save this notebook, and launch VS Code with only this notebook open

Exception:

2024-11-25 12:23:42.755 [error] ReferenceError: Cannot access 'defaultLanguageId' before initialization
	at updateQSharpCellLanguages (http://localhost:3000/static/devextensions/out/extension.js#vscode-extension:40620:57)
	at eval (http://localhost:3000/static/devextensions/out/extension.js#vscode-extension:40577:7)
	at Array.forEach (<anonymous>)
	at registerQSharpNotebookHandlers (http://localhost:3000/static/devextensions/out/extension.js#vscode-extension:40575:40)
	at activate (http://localhost:3000/static/devextensions/out/extension.js#vscode-extension:40979:33)
	at async F1.n (http://localhost:3000/static/build/out/vs/workbench/api/worker/extensionHostWorkerMain.js:113:4450)
	at async F1.m (http://localhost:3000/static/build/out/vs/workbench/api/worker/extensionHostWorkerMain.js:113:4413)
	at async F1.l (http://localhost:3000/static/build/out/vs/workbench/api/worker/extensionHostWorkerMain.js:113:3869)

---

The bug comes down to this sort of pattern causing an exception in JavaScript:

foo(); // ReferenceError: Cannot access 'x' before initialization

let x = 1;

function foo() { x } 

Fix is to declare defaultLanguageId at the global scope so that initialization is guaranteed before the function that closes over it is ever called.