Cannot run unit tests with Visual Studio Code

[haykam821]

With a simple JUnit setup, tests will crash on start:

java.util.ServiceConfigurationError: org.junit.platform.launcher.LauncherSessionListener: Provider net.fabricmc.loader.impl.junit.FabricLoaderLauncherSessionListener could not be instantiated
java.lang.RuntimeException: Duplicate setLauncher call!

This issue was previously discussed on Discord.