fix/set saved loading issue

[joshua-dean]

Fix set_saved issue with legacy submit button format

Description

SubmitButtons toolbox item can accept just a function instead of submit button items. The check for this happened after the #196 fix, which subsequently broke everything in these cases. Re-arranging the checks fixes this.

This one is on me for not properly testing all of the demos with features like this. I've tested all the demos with this fix and they are back to functional again.

Other additions

Added a build-dev-and-demo script to get better stack traces when I obliterate main like this

PR Checklist

• Merged latest main
• Version number in package.json has been bumped since last release
• Version numbers match between package package.json and src/version.js
• Ran npm install and npm run build AFTER bumping the version number
• Updated documentation if necessary (currently just in api_spec.md)
• Added changes to changelog.md

Breaking API Changes

nope

[TrevorBurgoyne]

good catch 👍