1 files changed, 10 insertions, 1 deletions
diff --git a/curling.rb b/curling.rb
index 4b03e8d..e688a01 100644
--- a/curling.rb
+++ b/curling.rb
@@ -61,7 +61,16 @@ To restart the game, run `rm k` to remove the cookie that stores your game state
 end
 
 get '/:command' do |command|
-  engine = Hex.new cookies.to_h
+  begin
+    engine = Hex.new cookies.to_h
+  rescue InvalidChecksumError
+    halt 422, <<~MSG
+      Invalid state, checksum does not match!
+      If you lost your last valid game state, you'll have to remove your current
+      cookie and start over.
+    MSG
+  end
+
   engine.step command
   engine.state_h.each_pair do |key, value|
     cookies[key] = value