src/vs/workbench/services/preferences/browser/preferencesService.ts/PreferencesService/openWorkspaceSettings
class PreferencesService:	openWorkspaceSettings(jsonEditor?: boolean, options?: ISettingsEditorOptions, group?: IEditorGroup): Promise<IEditorPane | undefined> {
		jsonEditor = typeof jsonEditor === 'undefined' ?
			this.configurationService.getValue('workbench.settings.editor') === 'json' :
			jsonEditor;

		if (!this.workspaceSettingsResource) {
			this.notificationService.info(nls.localize('openFolderFirst', "Open a folder or workspace first to create workspace or folder settings."));
			return Promise.reject(null);
		}

		return jsonEditor ?
			this.openOrSwitchSettings(ConfigurationTarget.WORKSPACE, this.workspaceSettingsResource, options, group) :
			this.openOrSwitchSettings2(ConfigurationTarget.WORKSPACE, undefined, options, group);
	}