Types of internal AST nodes

[wytseoortwijn]

Internal AST nodes sometimes throw violations when encountering an unexpected type. See for example:

https://github.com/viperproject/gobra/blob/26d14130b7b757648e62b7a5a6ff24ace342b1e7/src/main/scala/viper/gobra/ast/internal/Program.scala#L258-L261

However, such code would fail if the type is wrapped into a defined type, like for example type T option[*int].