Follow-up to previous rev. fe1f5c439689.

addon/content/TbHelper.js

@@ -63,6 +63,7 @@ const TbHelper = {
     // The deletion happens in `OnStopCopy()` of the copy listener for local messages
     // and in `OnStopRunningUrl()` for IMAP messages if the folder is displayed since
     // otherwise `OnStopRunningUrl()` doesn't run.
+    let newKey = null;
     const deleteListener = {
       QueryInterface(iid) {
         if (iid.equals(Ci.nsIMsgCopyServiceListener) || iid.equals(Ci.nsISupports)) {
@@ -72,7 +73,7 @@ const TbHelper = {
       },
       OnStartCopy() {},
       OnStopCopy() {
-        if (selectNew && win && win.gDBView) {
+        if (selectNew && newKey && win && win.gDBView) {
           // Display the new message.
           controller.log.info(`Selecting new message with key ${newKey}`);
           win.gDBView.selectMsgByKey(newKey);
@@ -80,7 +81,6 @@ const TbHelper = {
       },
     };
 
-    let newKey = null;
     let statusCode = 0;
     let deletedOld = false;