Fix localStorage error in incognito window

[oeway]

When using cellpose in an incognito window, the browser blocks access to localstorage and complaining the following error:

DOMException: Failed to read the 'localStorage' property from 'Window': Access is denied for this document.
    at https://www.cellpose.org/static/imjoyAPI.js?20200915f:118:32
    at new Promise (<anonymous>)
    at Object.showConfig (https://www.cellpose.org/static/imjoyAPI.js?20200915f:112:18)
    at https://cdn.jsdelivr.net/npm/imjoy-rpc@latest/dist/imjoy-rpc.min.js:1:7105

This is a fix to allow save settings to fail.