extensions/markdown-language-features/server/src/workspace.ts/VsCodeDocument/getText
class VsCodeDocument:	getText(range?: Range): string {
		if (this.inMemoryDoc) {
			return this.inMemoryDoc.getText(range);
		}

		if (this.onDiskDoc) {
			return this.onDiskDoc.getText(range);
		}

		throw new Error('Document has been closed');
	}