src/vs/workbench/api/common/extHostNotebook.ts/ExtHostNotebookController/getEditorById
class ExtHostNotebookController:	getEditorById(editorId: string): ExtHostNotebookEditor {
		const editor = this._editors.get(editorId);
		if (!editor) {
			throw new Error(`unknown text editor: ${editorId}. known editors: ${[...this._editors.keys()]} `);
		}
		return editor;
	}