Fix Empty Editor State Bug

[thecoolwinter]

Description

If a workspace is closed via an application quit with a split editor, the editor will allow the user to close all editors when the app is re-opened. This leaves the workspace completely unresponsive with no active editor splits.

To fix, moved logic that should be in EditorManager into that class and cleaned up some files, then added a private state variable to EditorTabBarLeadingAccessories that tracks an "other" editor if it exists. It updates that state variable when the editor manager updates at all now instead of doing the check on a view update.

Related Issues

• N/A, discovered while implementing tests for the editor UI.

Checklist

• I read and understood the contributing guide as well as the code of conduct
• The issues this PR addresses are related to each other
• My changes generate no new warnings
• My code builds and runs on my machine
• My changes are all related to the related issue above
• I documented my code

Screenshots

main build, after quitting the app with a split open:

editor_layout_broken.mov

Fixed:

editor_layout_fixed.mov

[austincondiff]

Looks really good but it looks like you have a small SwiftLint error.

[thecoolwinter]

@austincondiff fixed!

[0xWDG]

LGTM