The parser should check when the keyword 'super' is used in an invalid context.

This gets compiled and crashes the program with a fatal stack overflow error.
override def ToString():
return super + " [$

]" # () are missing

It generates:
public override string ToString()
{
return (((string) this) + new StringBuilder().Append(" [").Append(this.lyrics).Append("]").ToString());
}

This should be caught at compile time. The error should say, "Use of keyword 'super' is not valid in this context," like C# does for 'base'.