fix: fixed an error that current graph state cannot be exported into JSON correctly

[WenhanLyu]

Description

When clicking the 'save' button in the ThemeToggle component, the getJSONState function will throw an error that the graph parameter is empty. This error is caused by getting the graph info with the incorrect graphKey; update it with the correct value will fix it.

Checklist

• [x] I've followed the Contributing guidelines

• [x] I've titled my PR according to the Conventional Commits spec

• [x] I've linted and tested my code