src/vs/workbench/services/history/browser/historyService.ts/EditorNavigationStack/goPrevious
class EditorNavigationStack:	async goPrevious(): Promise<void> {
		const navigated = await this.maybeGoCurrent();
		if (navigated) {
			return;
		}

		// If we never navigated, just go back
		if (this.previousIndex === -1) {
			return this.goBack();
		}

		// Otherwise jump to previous stack entry
		this.setIndex(this.previousIndex);
		return this.navigate();
	}