Linking edge case

src/js/HuesEditor.js

@@ -712,7 +712,8 @@ HuesEditor.prototype.uiCreateEditArea = function() {
     // CHAIN-BROKEN, use  for CHAIN
     let locker = this.createButton("", this.timeLock);
     locker.addEventListener("click", () => {
-        if(!this.song) {
+        // Only allow if both song bits exist
+        if(!this.song || !this.song.buildup || !this.song.sound) {
             return;
         }
         this.setIndependentBuild(!this.song.independentBuild);