To Reproduce:

1. Create a new project, add a new script with these two classes:

public class foo<T> where T : class
{
private List<T> foolist;
}

public class bar : foo<bar> {}

2. Build to WebGL, notice the 'Error building Player: Exception: IL2CPP compile failed.' and 'Failed to run python' errors.

3. Builds fine if the second class 'bar : foo<bar>' is commented out.