Improve error message if the dependent world is changing and incopatible with previous attemp at importing #11
Description
As I try and get my World etc. right, I'm continuously trying to import it to a Spin component using spin deps add.
At a given point I ended up with this error:
Error: failed to merge package `root:component` into existing copy
Caused by:
0: failed to merge world `dependency-world`
1: import `advent-of-spin:challenge-two/non` not found in target world
It would be good to expand the error message telling the user where the root:component world can be found - .wit folder, and even better a way to just undo as a command.