There were a handful of concomitant improvements: * The printing of error message has been improved to display the code source responsible of the error outside

There were a handful of concomitant improvements: * The printing of error message has been improved to display the code source responsible of the error outside of the REPL. * Some probable beginner errors (like discarding a non-applied function with `ignore`) now raises a warning. * Type name captures should not happen anymore in error messages: no more `val x: int` is not included in `val x: int` where `int` refers silentiously to different types. * A handful of typing errors has been fixed to speak to users and not the compiler developers (no more "unexpected existentials" for instance). * Some compiler internal change to make it much easier to use the typing context when explaining a type error. This is not used much yet, but I hope to improve the scope related type errors in the next versions.