src/vs/workbench/api/browser/mainThreadDocumentsAndEditors.ts/MainThreadDocumentAndEditorStateComputer/_onDidRemoveEditor
class MainThreadDocumentAndEditorStateComputer:	private _onDidRemoveEditor(e: ICodeEditor): void {
		const sub = this._toDisposeOnEditorRemove.get(e.getId());
		if (sub) {
			this._toDisposeOnEditorRemove.delete(e.getId());
			sub.dispose();
			this._updateState();
		}
	}