When user uploads project file, project will auto-save before loading

[benjiwheeler]

Resolves

• Resolves Upload from your computer does not save the current project #4120

Proposed Changes

• adds several states to project-state reducer to handle file upload
• introduces ability to indicate that a project load failed, and then to return to normal state with currently showing project; we should discuss this
• refactors sb-file-uploader so that it syncs with project-state state machine

Note that the titles still aren't set right; we could add that here or do it as a follow on. But, at least now the old project's title isn't overwritten.

Basic functionality: uploading a project saves current project first

The original project is indeed saved correctly:

Uploading a second project file, with no page reload (so keeping the same FileReader object), works correctly:

trying to upload an invalid file fails without taking you away from your current project:

Reason for Changes

current project wasn't being saved before uploading project and saving as new project

Test Coverage

Adjusted and added project state reducer tests

Browser Coverage

Check the OS/browser combinations tested (At least 2)

Mac

• Chrome
• Firefox
• Safari

Windows

• Chrome
• Firefox
• Edge

Chromebook

• Chrome

iPad

• Safari

Android Tablet

• Chrome

[paulkaplan]

Travis tests are failing

[paulkaplan]

@benjiwheeler I noticed that this causes a regression where the project title does not get updated in the standalone editor. If possible, I think we should get this in without introducing a regression. This will, for instance, break the Scratch Desktop functionality

[benjiwheeler]

I was trying to keep this change focused to fixing this one issue and not the title-switching one; I can't keep the current functionality. But let me try fixing that too, here -- it's probably not so hard.

[paulkaplan]

@benjiwheeler yeah, it's just it is hard to revert PRs that break one thing in favor of another. We have to fix both before either goes in I think, so let's just include both here

[paulkaplan]

Yay! Looks good now. Let's get this to staging for some 👀👀👀👀 /cc @BryceLTaylor

[benjiwheeler]

Just waiting for tests to pass, then will merge