Server: disallow moving from an empty location

diff --git a/trivabble-server.js b/trivabble-server.js
index 6f511e3bc4cbd38e512c535ba8c749cca44656d5..e7333b71f9bfa927d39348aaaae75e1ea06fb360 100644 (file)
--- a/trivabble-server.js
+++ b/trivabble-server.js
@@ -567,6 +567,12 @@ function handleCommand(cmdNumber, message, response) {
                     }
 
                     letter = rack[cmd.indexFrom];
+
+                    if (!letter) {
+                        reply(message, response, cmdNumber, {error: 1, reason: "Moving from an empty location"});
+                        return false;
+                    }
+
                     operations.push(() => {
                         rack[cmd.indexFrom] = "";
                     });