1. Create a new project
2. Go to Edit -> Preferences -> External Tools and change "External Script Editor" to "Visual Studio Code"
3. Create two new scripts
4. Open them both with VSCode editor in Unity (they should remain on the tabs of VSCode editor)
5. Close VSCode Editor and reopen one of the scripts

Expected result: when closing VScode editor in Unity, the opened scripts remains on the tabs of VSCode editor
Actual result: closing VSCode editor and attempting to open a script via the Unity project folder will open a new workspace.

Reproducible with: 2017.4.14f1, 2018.1.9f2, 2018.2.14f1, 2018.3.0b8, 2019.1.0a7