Before doing anything, check if we COULD start

lmm/cli.py

@@ -39,6 +39,15 @@ def launch(game: str, profile: str):
         click.echo("Profile not found")
         return
 
+    # Check if the game can start.
+    if not game.can_start():
+        click.echo("Cannot start game:")
+
+        for issue in game.cannot_start_reasons():
+            click.echo(issue)
+        return
+
+    # Check if we have a runner available.
     runner = None
     if profile.runner is not None:
         runner = profile.runner